Connections are dropped all the time, and then your code, on both client and server, need to account for retries (will the reconnection use a cached DNS entry? how will load balancing affect long term connections?), potentially missed events (now you need a delta between pings), DDoS protections (is this the same client connecting from 7 IPs in a row or is this a botnet), and so on.
Regular polling great reduces complexity on some of these points.
Connections are dropped all the time, and then your code, on both client and server, need to account for retries (will the reconnection use a cached DNS entry? how will load balancing affect long term connections?), potentially missed events (now you need a delta between pings), DDoS protections (is this the same client connecting from 7 IPs in a row or is this a botnet), and so on.
Regular polling great reduces complexity on some of these points.