Hmm thats good and bad, not sure I want my acks to be manipulated by the isp. How much shared upstream is there if you dont mind answering? For some reason I cant find this info, I remember a decade ago this stuff was much easier to find.
Each CMTS has multiple 10G uplinks. Each cable segment has 4-6 x 27 Mbit/s upstream channels. A single Gig1 user has half the capacity their modem is addressing. VM have major problems with network noise due to regulation preventing them taking stronger measures to remove it.
The acknowledgement suppression has been a thing for 20-odd years. It doesn't break anything.
EDIT: It's also not done by the ISP, cable modems do it. Rather than sending every acknowledgement separately if they have acknowledgements arrive while waiting for upstream slots they'll acknowledge everything cumulatively. Saves upstream capacity all around.
Also on the matter of the guide I'm going to cut the guy all the slack in the world given he gave us
https://bidb.uk/