There's likely always a line somewhere where effort becomes way out of proportion compared to getting that last mile effort.
Arguably, if you only have a website, that won't work for anyone without access to the Internet. So then you should have a physical presence in each of those people's location, and arguably you shouldn't provide any improvements that give me more than physical presence does, so you should not have the website in the first place, since people without the Internet can't use it or you have to keep your website without any improvements over the physical office.
If you only have a website, arguably 2+ billion people currently wouldn't be able to access it.
And it seems odd to bring 150 mil people as an example, when the baseline should be at least 2+ billion with website only.
Not using bleeding edge web "standards" is also hardly comparable to the office of having a physical presence in every locale though. Software developers seem to be uniquely good ad overvaluing small convenience gains for themselves compared to the pain inflicted by breaking compatibility multiplied by the set of affected users.
Most websites are glorified rich text or forms. And most of the rest should be that. This is even more true for the kinds of websites people need to use rather than some designers art experiments. They don't actually need all these fancy features except to make their developer's work slightly easier.