Why go with Coinbase when they already have their own platform where you can stake your ATOM there.
I'm also staking some ATOM tokens in their own wallet called KEPLR. Currently, I'm on the node of Binance which gives 19.12% annually. I might un-stake it, and find another node since Binance node doesn't support airdrops from Cosmos. There is this feature of the project where those who are staking their ATOM tokens has the opportunity to get some free tokens thru airdrops.

Why they don't just buy cryptos that they can stake? I don't know the exact reason TBH, but maybe it's because they didn't do any research in any of these staking coins, and they with other projects. Most of the top 20 coins right now base on market cap offers staking, so TBH I don't know the main reason.

I would call myself a hypocrite if I will say no to it since I myself is also doing it.

The problems that I'm seeing with these staking coins is that, there is a chance that you might get an impermanent loss while staking it, and the amount of coins that you are getting for free isn't enough to cover your losses, and the other one is when the project turns out to be a scam project. I would advice to do it, but just be ready for the risks of staking.