Yes, any advertising in the base operating system is totally unacceptable since it means the OS is tailored to the needs of the advertiser instead of those of the user. The base operating system - that is everything needed to run the system as normal without compromising on functionality - should be a clean slate as far as advertising, and 'telemetry'/user data exfiltration is concerned. If a user wants to install anything on top of that base system which comes with advertising that is his choice but the base should be ad-free.

Easily removed, but new microsoft software seem to be magically added by default, and if you have to maintain a number of non-enterprise windows 11 installs, it suddenly becomes a game of whack-a-mole across multiple machines.

I'm happy for updates for existing software, but I draw the line at them adding new things that I can just remove in 30 seconds over and over again.

Yes, advertising is unacceptable. It's annoying, it's distracting, and it's an infosec risk.