"Chrome based" isn't an issue, the rendering engine in chromium works fine, and the ad platform is just being built into chrome not the other browsers based off chromium.
There is an issue with monoculture of rendering engines.
Developers assume every browser have the same things implemented and start to build around this assumption. Also Google can dictate how the web looks like.
Creating artificial "feature" based defacto standards
Chrome offers adherence to standards as one of their features. But it also introduces new features that look like standards, meant to increase profits for the parent company.
Chrome offers adherence to standards as one of their features. But it also introduces new features that look like standards, meant to increase profits for the parent company.
VB.Net was exactly that. Difference being Microsoft's interest was locking companies and governments onto Microsoft's enterprise products vs Google's user tracking. Easy, quick internal web app put together in half a day? Would never work right on Netscape. It takes work to make them work to standards.
Using chromium based browsers keeps power over web standards and such in google's hands, i.e enforces their ever growing monopoly. So if you want a competitive/fair environment on the web, it's best to avoid them altogether and stick to firefox or safari.
Funny you mention Safari, because you know, Safari is the only browser allowed on iOS. Every other browser has to use Safari to render web pages if they want to be in App Store - once again the only allowed source of packages.
Safari on iOS is literally worse than IE and Chrome combined.
Unfortunately for Android, Chromium based browsers are, at the moment, significantly more secure than Firefox based ones.
Edit: For the people down voting me, feel free to make a principled stand to avoid Chromium browsers on Android, just understand the risks. Again, specifically for Android. Here's some reading:
Unless the developers of other browsers take specific steps, the ad engine will get pulled on the next update of their Chromium engine, that's the problem.
They have forked it though? That's why almost all the other Chromium-based ones don't have this enabled by default or completely disable it (even if you tried to turn it on).
If you're talking about forking the entire project and using it as a base that diverges from what Google does, I don't think that's going to happen. Not even Microsoft with their billions had the desire to maintain a totally separate engine anymore and I don't see the other Chromium-based browsers redirecting efforts from useful things like better UIs, privacy enhancements, etc into just keeping feature/performance parity.