People, who choose Chrome (not even Chromium) over Firefox for a fraction of a second faster load speed of some pages (, which is often even "fake" as Google artificially slows down some pages for Firefox users or engineers them in Chrome optimization specific ways,) disregarding any privacy concerns, are simply not the target group of Firefox developers, because they do not care about privacy enhancing features. To sacrifice ones rights to gain tiny speed improvements or often only the feeling of being faster – It is simply a laughable trade-off to make. Many people and even institutions of education, which should know better, choose to do so apparently.
If one is concerned about privacy and data being sent to Google using FF, well, there is always IceCat. Managed by the people, who stand most firmly for your rights in computing and software. GNU.
It is also quite well known, that Chromium and Chrome are memory hogs. One OS process per tab? Really? I've also not read anything about improvements on that front in the last many months, while at least with Quantum the FF developers aim to keep memory usage low and cores optimally used - at least in their pitch.
I think Chromium has a long way to go, before it gets close to low memory usage for many tabs scenarios. As a tab hoarder and curious person, memory usage patterns like the one of Chromium are not acceptable. I am sitting on 238 tabs in IceCat right now and 33% of my 8GB RAM are in use, with several other applications, including one electron based open at the same time. No problem whatsoever to have my browser and multiple other memory intensive applications open.
The same seems infeasible with Chromium and its forks. I've seen it with double of my RAM and much less tabs on a co-worker's machine. Chrome just ate all of his RAM. I cannot remember, whether it crashed then, or he had to close the browser, to continue to work. Both are quite disruptive for getting things done.
I think FF devs have done a great job with Quantum. Unfortunately one cannot always trust Mozilla entirely (see some cases of "studies" and the money they get from Google), although they often do great work and enhance online privacy. For me it seems the better option to stay behind a shield of people, who take privacy and user rights very seriously and remove telemetry and similar things from FF and use the outcome of that.