It’s slow to adopt new standards and a pain to develop for, but as a bit of consumer software it’s the best browser out there IMO.
I don't see why number of commits would be anything but an extremely weak proxy for estimating power consumption, certainly not anything to cause surprise. A very strange thing to say by a self-described "rationalist". "Optimizations" is a very wide term you've used. Unless you are specifically targeting power consumption, it's quite possible to optimize for speed and markedly increase power consumption.
Even as an user, if I want adblock, it will launch separate application, with separate dock icon. That's so un-Apple, as if they didn't want you to use it.
I find Firefox's Dev Tools far better, except the JS debugging tab, which is behind Chrome's on almost all counts.