These are the perfect answers, but I am not sure about the number 4 if there is.
Why not? Some whales use them and its like fanservice to keep them addicted to their favourite exchange. Even casinos give out promos to keep their customers.
If someone avoiding KYC verification I think Decentralized exchange or a quick one is P2P exchanges.
DEX or CEX does not really matter because exit scams occur in both. We are nowhere near any regulation so one should use what is suitable instead of using a certain exchange only to dump shitcoins.
Just a tip in regards to the support, the closest way to get a gist of its current state is to try it yourself, maybe inquire about something and read the complaint threads of their users which they have replied to. Don't dismiss every "resolved" thread as a good thing right away, pay attention to the content, how they reply and how long did it took, there are some cases when it's blatant that they are just giving excuses after excuses.
Some noobs attempt to make the exchange looks bad without providing proofs. These should be disregarded as trolling than anything that is a legitimate issue. Do most exchanges have a forum of their own or allow reading support tickets of other users? I doubt it. What we see on this forum may not always be a proper support system.