Because what answers the prayers is no longer a parasitic anti-life creature that seeks stagnation and the annihilation of freedom to ascent, combined with destruction of all forms of sentient life.
Replacing that at interface level (so to speak) when 99% of the current people try to contact is the godhead within themselves anyway, is not difficult.
For the rest, I will only say that there’s a lot of confusion here between the nature of a god or spirit, and that of an idea, which probably stems in equal parts from confusion over the Divine Paradox (no offence) and chaos magick getting worked into things.
Can a human stand up after maybe 2 months’ or 2 years’ practice opening sigils and say “I’m going to kill a god today” and succeed, alone, and just because they felt like it?
Possibly not.
Can several humans, supported by ancestry back through time and a veritable army of other gods, demons, nature spirits, etc., battle a wholly parasitic being so thoroughly, whilst allied forces replace it in all areas where people will attempt to recreate it, that it is entirely destroyed?
I state yes based on experience, observation, and actual practice, which came after some 25 years of being dedicated (in increasing amounts) to that specific aim.
But to argue that point any longer is undignified, and would increasingly require me to share things I work hard to forget regarding the nature of what was done. I logged my experiences in this thread back in 2016, and that’s about as much as I want to share on ’em. 
Constructively, I think a good test for delusion regarding a piece of work may be:
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Can you function normally in life without thinking about the (whatever) for periods of many days at a time?
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Do you have solid self-worth, including the ability to accept flaws, and find rewarding experiences and fulfilment in areas unrelated to (whatever)?
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Do you have realistic goals in mundane life and magick that are not escalations of (whatever) and are not related directly to it?
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Are you able to maintain civil conversations with people who are not aware of, or do not essentially accept, the reality of (whatever)?
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Did anyone else witness (whatever) in a way that could not be due to prompts or other shared information received prior to this?
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Did previous events in your life over a period of several years lead up to (whatever), without you being consciously aware of this?
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Have any changes manifested in the observed reality of others that correspond to the expected results from (whatever)?
Where I have observed people who have a delusional belief about something, they usually fall at 2 or 3 of these hurdles, at least – in some cases of people who have been on this forum, more than that.
Just spitballing though, so long as someone is happy and not being rude or obnoxious on here, they might as well believe some crazy shit.