Especially since they can/do also target any of your secondary accounts, and can also hit family members depending on various backend circumstances that users can't really know about.
Regardless of the fact that you can find some sort of replacement for any of those things individually, it would be a major stumbling block and disruption for most users to suddenly no longer have access to their email/history.
The average person does not have forwarding or mirroring of all that stuff set up. I posit that that disruption is enough of a deterrent to get users to stop using ad blocking on Google services once the consequences start being applied.
Though that reminds me, I don't quite know what happens to your chrome bookmarks and settings if Google obliterates your profile's account. I assume that merely syncing will stop working, but perhaps more might be disrupted.
You know you fail when you gimp your free service and allow users to ungimp it for cash, while someone else ungimps it better for free.
Big corps never understood this, with Valve being the only counterexample I can think of.
Blocked by: SponsorBlock
Next?: YouTube making it harder to skip around video
Blocked by?: Zoomers just alternating between videos, cutting in and out while the ads “play” silently, because they can never get enough dopamine
Even the concept of "changing the channel" is something to eventually lock down in this way; don't let the users change tabs or modify the window or display state at all until trusted ad content has verifiably finished.
The saving grace is that you'll probably be able to just get up and walk away until it's done, at least for some time.
There has to be a reason why they haven't done that already. Perhaps they haven't worked out a reliable way to track ad impressions in the continuous stream. Perhaps they got it working but it's too resource intensive at scale.
Given the magnitude of revenue at stake, the other shoe should have dropped by now.
It's just the market pressure to generate even more every quarter.
There are ways around this and ways to still generate profits.
It's not like nobody was watching ads. It's not ever ENOUGH people to watch ads because you have to deliver more for the shareholder horde.