If you have excellent conditions and apply for EA/ED, the school will admit you in advance to ensure that you will choose this school.
If your condition is that you will meet his admission criteria, then the school hopes to put you in the pool of RD and have a look again. If most applicants for RD are better than you, then the school will admit those people and reject you. On the contrary, the school will admit you.
This is actually the same as shopping. The school is a customer with a limited budget. If you meet a product you like enough, you will naturally buy it on the spot. This is EA/ED admission; If it is only possible, you will remember this product and continue to shop around. This is an extension; If you meet something better in the future, give it up. This is RD reject after defer. If you don't meet something better, come back and buy this. This is the third acceptance after the postponement.
According to statistics, the possibility of rejection after the extension is very high.