That’s up to 30K dynamic rules, at least 30K static rules, and at least 1K regex rules: https://developer.chrome.com/docs/extensions/reference/api/declarativeNetRequest#property-GUARANTEED_MINIMUM_STATIC_RULES
That seems like it’s fine for general use, and those limits might go up again. EasyList and the other big lists can be consolidated to varying degrees with Chrome’s rules format, and there’s probably some dead rules in there. uBlock Origin on Firefox will definitely be more versatile moving forward, but every time I’ve used uBlock Origin Lite in Chrome it’s almost the same experience.
YouTube launched in 2005 and was bought by Google in 2006. It has been a Google service for 95% of its existence. I’m pretty sure Google did other stuff in that 18 years than “put in more ads.”