Unfortunately for Mozilla, the reality is that Google, with its combination of large marketshare, aggressive timelines, and wide platform penetration (on both their own first-party and others' third-party platforms) had accomplished more in enhancing the capabilities of code loaded by the Web: they develop all sorts of APIs to expose native platform functionality inside Javascript running inside the browser, ship them in Chrome, then submit most of them to W3C and evangelize their merits. The most trashy ones they deprecate in two or three years, replace it with a different, incompatible take, and remove support for it in a few versions.
The author's 'Lessons Learned' section reads as a wishful vision of web browsers themselves, which, is both surprising in its lack of differentiation, and yet simultaneously ambitious in its hopes of being able to culture a... what's the word? 'platform'? 'ecosystem'? 'environment'? where well-executed server-side technologies interact with thin but slick clients; how is this different from the existing web and its browsers again? Does the point then become to offer a FOSS low-level system OS on top of which a browser can run? Isn't this one of the few successes of B2G, yet also operates in a space entirely dependent on the whims of hardware vendors, and competes with the likes of Tizen, Sailfish OS, AOSP, and the Linux kernel itself?
The retrospective is interesting: a dissenting opinion from an inside source, and it definitely sheds light on some important details that were glossed over or ommitted from the more 'political', corporate communiqués. But the conclusions are unsatisfactory: the preferred outcome reads less like "Boot to Gecko" than "Boot Only to Gecko", which sounds a lot like Chromebooks. The difference being, of course, that Google has a diverse (if frequently culled) selection of web-accessible services that together can be used as a computing and browsing platform, feeding search and browsing metadata and usage habits to Google thanks to the power of defaults. What could Mozilla have offered in this space to realistically take on the exact same frenemy with a larger warchest?