Even if Mozilla were to bundle ublock into the standard Firefox install, it probably wouldn't matter. As much as I love using it, its marketshare has been on a slow spiral for a while, down to 4-8% right now. I'm willing to bet a decent proportion of those users already use some form of adblock due to the frequency of obscure Firefox only issues I've seen, which tend to push away non tech folk. I've never met a non technical person who prefers Firefox. Because every now and again, you'll run into a website that renders wrong or shows you a scary popup for having a non Google user agent. Or you'll run into issues with proprietary drm solutions that were only tested under Chrome. Or you'll get lots of the obnoxious "click on all the sidewalks" captchas, which won't happen on Chrome unless you use a sketchy VPN service.