Which we know from the IE dominated era does not matter, people just switch to the browser they have to use. The overwhelming majority of users do not know what a user agent string is, let alone how to change it they just see an increasing number of sites saying "you need to use IE/chrome".

Moreover, again from the IE era - and we already see this with chrome - people make their sites work in IE/Chrome and then label any browser doing something different as broken so as people are increasingly forced to use chrome the degree to which spoofing does not work steadily increases.

True, it works in cases where you have to use the website, e.g. for work. But generally I would avoid such websites as much as possible.