[devit]

They could, but they don't want to do that because they get paid by Google to not do it or because those actions get them money in some other way (from advertisers or whatever), or because they think only power users like some features.

[glenstein]

Firefox publishes their 990 form which discloses all their sources of revenue and Google does not pay Firefox for any of the things you described. Also, it feels kind of nonsensical to suggest that it would have a development strategy of building out their ad tech and simultaneously reverting it, and I don't see how explanations about them wanting or not wanting to do it make that proposed approach for any more sense.

[devit]

They pay them for making Google the default search engine, and it is hypothesized that the payment may also influence them to not provide ad-blocking by default and possibly other things that are not beneficial for Google's business.