web cesspool servers send data in big chunks/high speed bursts, which is not compatible with constant rate links.
Go play packet filter rate limits, works fine.
your ISP rate or physical link speed already serves as max rate
people could generally send dummy traffic to eacht other at the max rate advertised by their ISP
They already send all kind of traffic to each other today. Go plug in your 100Mbps NIC, go buy 10Mbps from your ISP, then go send 10Mbps worth of whatever you want between whoever you want. Works fine.
you can't just foward traffic from the overlay to the arpanet web cesspool and expect anonimity
That's further approachable with some network fill design than it is with tor or anything else today that do nothing. Possibly even a 10x odds reduction or more.
Services that don't require high speed/high volume traffic, like, say, mail, may be fine. 'Bursty' traffic won't work.
Define 'bursty'. Anything three packets or more might be considered as such. An email message is a lot of TCP packets, go plot their traffic curve. Go play with packet filter rate limits, introduce and give a wheat flow priority over a pipe that is already maxed out with a chaff flow, watch the flows trade off.