Well those are good interest rates you will earn if you do stake alts like tezos and eth. I did useed to stake coins on a exahnce but now I like to have full control of my coins.
There is still alot of people that does stake coins on exchanges and ledger. But there is people that will not stake just because we never know what is going to happen to those coins.
And it can take some time to get them back if they are being staked. You can stake if you want but it is a good reason you will get those good rates to do it.