Hello! Interesting Q, my thoughts:-
I have several relatives who have prayed the sinner's prayer at a meeting, but afterwards have never darkened the door of a church, nor do they have any desire to. One cousin describes his experience as 'having got his ticket', (the idiom that the speaker used, put up your hand for a ticket to heaven) that is his sum of interest in having a spiritual conversation, he's engaged to be married to a pagan.
I don't think they can be blamed, it's how the message is presented to them. To begin with it shouldn't be presented as a message. Faith comes by hearing and hearing by the word of God. God commands all people everywhere to repent, he doesn't invite them to accept a synthetic message.
Quite often the speaker at an event will talk about themselves, a 'testimony' that may well be embellished and cannot be verified. It's a human-centered message, reversing the God centered word of the bible-
God wants to do wonderful things for you because you're great.
I went up to heaven and rode on a dinosaur with Elvis, I was down to my last dime and found a wad of notes in my bible, you can too, all you have to do is put up your hand. It's emotionally driven, with psychosomatic or psychedelic repetitive music, the whole set up designed to produce a feeling of euphoria and massage someone into a decision. Not to repent and be converted, but a decision. Invite the Jesus of the speaker's imagination into your heart, don't worry about the Jesus of revelation in the bible. The brain is switched off, not the 'Come let us reason together' or 'Be transformed by the renewing of your mind' of the bible. The speaker could stand up and claim anything, it's a complete monologue by a professional salesman with no scrutiny or corporate accountability. If they are caught out having 'misspoken' it doesn't disqualify them from anything.
Apart from what is said, that which is not said also speaks volumes. Repentance, turning from sin and righteousness, sacrifice and service, those legalistic old fashioned Biblical ideas, they'll turn people off. Just talk about worldly success, money, getting a better career, prosperity, getting ahead in life. All the things that the sin nature wants.
At a basic level if you have a bottle of medicine and dilute it one hundred times, more people will be able to drink it but it will lose it's efficacy. If you tip the medicine out and fill it up with sugar-water it will taste sweet, but apart from rotting your teeth it won't do anything. God Bless