Long polling has nearly all the same disadvantages. Disconnections are harder to track, DNS works exactly the same for both techniques, as does load balancing, and DDoS is specifically about different IPs trying to DoS your system, not the same IP creating multiple connections, so irrelevant to this discussion.

Yes, WS is complex. Long polling is not much better.

I can’t help but think that if front end connections are destroying your database, then your code is not structured correctly. You can accept both WS and long polls without touching your DB, having a single dispatcher then send the jobs to the waiting connections.