You're assuming that ISPs are okay with you hosting a public service using their infrastructure, which they're historically very much opposed to (in order to get you to pay for a more expensive "business" account).
Mine doesn’t give a crap if my outbound is 200 gig a month uploading stuff to onedrive or iCloud. Why should it have that opinion on anything else? I’m paying for a pipe. The only control metric they have is asymmetry and that’s a technology tradeoff in my case (ADSL)
Oh I completely agree with you that they shouldn't care, but the odds are big that you'll find out that they do in your Terms of Service.
I never had issues running public http servers on residential isp connections. It's fine unless you get massive traffic.
Dude screw ISPs. Mesh networking will power the last mile soon.