I'd say: configured their browser to work like a browser instead of like a platform to run arbitrary code from the Internet.

Ideally we should be able to trust most of the web sites we visit. The last few years have shown us this is a bad idea, here are my two top reasons:

- security: while I'm personally less concerned with reasonable ads there are a number of problems with ad technology, like infectious ads and creepy tracking.

- a bigger problem for now IMO: poorly written web apps that makes the machine noticably slower.

Anyway, for public facing sites and apps, you may already be doing most of the necessary work for SEO purposes. Letting humans access the version that you're showing to search engine spiders shouldn't be a huge burden.

No, for the people who can't afford to upgrade to the latest technology.