DeFi hype will surely fall in next line but since we are fully aware on how this market works then it wont matter as long you do know on when to get out and make profits.
You might be fully aware about how the DeFi market works (I'm assuming that's what you meant), but I'm sure as hell not. I've done just a little bit of reading on it and have an extremely low-level understanding of how it's supposed to function, but the vibe I'm getting from it feels very much like the ICO craze, which has been mentioned multiple times in this thread alone.
Of course the top-name exchanges are jumping into DeFi tokens. If they don't, they're going to be losing out on enormous profits, as I'm sure they see another crypto craze forming.
Exhange are profitable institutions, it does not matter to them if the user made a loss or profit, but rather won more money, and thus add of any project that could achieve that profit.
Hell no, it doesn't matter to them whether there's any quality behind the token. The only thing they care about is its trading volume, which is where the exchanges make their money.