>no excuse
Are you sure about that? Yeah if your site has possibly sensitive data or deals with login data, HTTPS matters a lot.
Thing is, there's still a sizable portion of the web that runs without HTTPS because for a static blog/site about boring stuff you really get no advantage on HTTPS besides "Chrome won't yell at you" (which to be clear, Chrome Being Annoying About It has been the larger push to HTTPS for this group of site operators).
> As far as I'm aware Chrome isn't trying to ban HTTP connections.
It's the long-term goal. The link says this specifically. Right now they'll do silent upgrades but the long-term goal is to show the current "insecure connection" interstitial for expired HTTPS certs.
Also, as has been stated in other places - intranet is a thing and deploying self-signed certs, especially on consumer intranets (who do need these things for setting up stuff like printers, home cameras and solar panels) is a complete crapshoot.
Windows has its own cert store, but so do Chrome and Firefox and you need it in the browser to work (plus adding it is really non-intuitive). Linux has no cert store if memory serves me right so you only need the browsers. Android requires digging in the system settings to add a cert and on iOS you need a provisioning profile to add any certs if I'm not mistaken. No clue about OSX.
To be clear there's mitigations - ie. Autotrust the reserved intranet/multicast TLDs (.intranet, .internal, .private, .corp, .home, .lan and .local - this list being taken from RFC6762, which is followed by the IETF even if they've never officially declared it to be in effect) or having a universally signed certificate for those domains that generates no records in the crt.sh log (this is why you can't always issue things for intranets with a public CA - all certificate requests to public SSL hosts like letsencrypt are logged).
Both would probably limit security but they're a big hurdle that needs clearing.