Anything non-standard will kill shitty middleboxes so I assume spamming packets faster than anticipated will have corporate networks block you off as a security thread of some kind. Mobile carriers also do some weird proxying hacks to "save bandwidth", especially on <4G, so you may also break some mobile connections. I don't have any proof but shitty middleboxes have broken connections with much less obvious protocol features.

But in practice, I think this should work most of the time for most people. On slower connections, your connection will probably crawl to a halt due to retransmission hell, though. Unless you fill up the buffers on the ISP routers, making every other connection for that visitor slow down or get dropped, too.

Doing that would basically disable the congestion control at the start of the connection.

Which would be kinda annoying on a slow connection.

Either you'd have buffer issues or dropped packets.