No faith declares a miracle true when it is happening. Its always after the alleged event has happened. The past is out of reach so its impossible to know exactly what went on. That can be taken advantage of.
To say God expressed his truth and love in a miracle is a bigger claim than saying Jake murdered Ann. Hard evidence is needed. Jake must leave DNA and fingerprints. God's involvement or presence is merely assumed. Faith is not about God but about what people want to think.
Even then you only get evidence that something happened that nature cannot do. You still have no right to base religion or doctrine on it. Think of how religion says that God offers signs that evil spirits cannot replicate. The answer to, "God alone can raise the dead and Jesus rose" is, "But evil spirits can make it look like he did." So he is a proper cheat. Or is it religion doing the cheating? Or both God and religion?
By default faith in miracles and the supernatural goes too far. Religion does not mind that but doesn't want it getting too obviously out of hand. It fears people saying that a miracle made people wrongly think a person rose from the dead. Perhaps fake memories were implanted. If secret miracles are happening then we can trust nothing and maybe a spirit put Jake's DNA on Ann.
Religion feels all that in its gut. That's why it compartmentalises. It picks safe miracles and picks a safe number. One way to do that is by keeping miracles in the past.
Another reason why religion partitions, is this. It would rather hear of a miracle and accept it than seek to see it is that it likes the story about the wonder more than the wonder. Also, it fears the wonder might not survive a thorough investigation. The story gets a level of cover, if there are lies or mistakes in it, when nobody can reach the same level of knowledge or experience as those directly witnessing it. Religion feigns confidence in the supernatural and enjoys the contrived feeling of confidence. There is a convenience in using a miracle tale to prop up your prejudices and what you want to believe when it is the witness who has do the hard work and suffer the scepticism and maybe abuse.
So many of us chase miracle and paranormal claims and will use them to make ourselves more interesting and to prop up our religious prejudices and notions.
Let us explore other reasons for the boundaries.
Most spiritual advisers in history have said that we should not want nature to change for us and that if we want something we should want it to come to us as if by natural means.
Take the occultists. They do not want a world where the egg may occasionally boil itself. They do not want a pothole to temporarily fill up so that they do not wreck their car. Take the devout. They do not want a world where the statue of Mary comes to life and cleans the Church floor. Or where God tells you that Jane has died, through the hairdryer. That would be too unsettling for when we know what to expect of the universe we can work with it. We want to put in the self-discipline that demands. Also, even if you think God boiled your egg, what did it is anybody's guess. Do you want a possible Satan to be doing it?
Another reason why I want to think that blind chance is paradoxically on my side, is how it powerful it would make me if it were true. I want to think I am special. My ego almost needs this affirmation. There is something off-putting about a sandwich materialising on my table. It implies the universe wants to help me the lazy way as if I am not worth the attention and it is calling me lazy too. Also, once nature can be broken, I wonder if the sandwich is really a sandwich and not some kind of clever fake. Also what if somebody can ask nature to kill me magically and get their wish? I want magic but not crazy magic. I want nature, of which I am are a part, to treat me as special. I want to be part of this special nature.
If nature takes a bit of time before giving you the bicycle you crave so much, why would you want a miracle to make it just appear for you? We surely know we cannot complain as long as we get it.
Our biology is part of nature and needs nature. We inherently need to get what we want from it. As long as the supernatural or paranormal acts in a way that cannot be distinguished from nature simply working on its own we do not mind. We want that. We need that.
APPENDIX: CONSIDERING, "A PARANORMAL ABILITY WILL NOT FUNCTION UNDER LABORATORY CONDITIONS IF TOO MANY DOUBTERS ARE IN THE ROOM"
We have learned that we don't want obvious magic. We prefer nature to act as if nothing otherworldly is happening and still give us what we want. We want magic and nature to be unified. That attitude should be able to stop the alleged power from working far more than doubt ever could.
Plus if you want to show your ability and you know that people will blame the psychic power of doubt if nothing happens then that is off-putting. You cannot have confidence in your powers if doubt can quench them. And you wonder if those who say you have ability but the doubt stopped it manifesting, are simply being dishonest. What is the point of a test to see if the paranormal is real if they start to reason like that? Yet they test. They are saying that even if the test shows up nothing, it still worked for it showed the power of doubt! All that lying and childishness would put you off letting your occult energy flow.
In that light, no psychic can really get tested in the right frame of mind - their frame or others. If doubt has the occult or unknown power to stop your psychic ability from giving results, then pro-paranormal researchers cannot argue that some studies show evidence of the paranormal. It would make no sense.
Why should the attitude of sceptics in the room wreck the results? There are sceptics outside the walls too! We only hear of the supposed ones in the room because it is convenient.
By the way, while the paranormal is often tested under laboratory conditions, the Catholic prophet and miracle-worker is not. Catholic miracles will not happen to a gifted investigator. They happen most often to some child who can be counted on to speak about them as children would.