Maaaaaybe. I think the actual advantages over other methods are fairly intangible.
If “surfing the web” required making many very small anonymous payments every hour then yeah, there’s advantages. I’ll admit that doesn’t actually sound terrible - I’d rather pay a few cents to read articles than the current advertising & subscription model.
As a solution for mozilla in isolation though, it would be an over engineered solution with too much baggage. Current mozilla users might have the aptitude for something like this but Mozilla wants to seduce a larger market share which is not people like us.
IDK about “legally obligated”, but certainly professionally and ethically obligated.
If someone commits a heinous crime, and you want them to rot in jail for 100 years, then you need them to have the strongest possible defence. Otherwise, they might be able to appeal their conviction, or the family of the accused may feel vindictive.
Basically, if you want justice you need the best possible defence.