Nobody is forcing us to use browsers from google or Mozilla.
We are all free to implement our own UA. The specs are all open standards.
What stops us from writing browsers is the sheer volume of time and effort required - hundreds of thousands of hours of highly skilled work. That is all.
In the absence of such an effort, we would be left high and dry, with no way to experience the web.
Fortunately, that isn’t the case, because some others have done the work and allow us to use their browsers.
For that, we might feel grateful.
We might also be wary, and try to be aware of any adverse consequences of using someone else’s thing. That’s common sense, but it is still not a case of being at someone’s mercy. That situation loomed when one company sought to control the standards for the web as well as the implementation, but what we have today is different to that.
The specs are open standards, but do the specs specific enough to actually do something that would work in practice?
By "work in practice" I mean handle most sites that people actually visit and display them almost identically to the way Chrome and Firefox do. If your new browser doesn't do the same thing as Chrome and Firefox on those sites, the users are going to perceive it as your browser sucking.
If Chrome and Firefox deviate from the spec in some way, you will have to match that deviation.
If there is something not covered in the spec but that browser have to deal with (such as handling malformed HTML, which a lot of sites have), you will have to match what Chrome and Firefox do there.
This feels like saying that you're not forced to be subject to the laws of your country, because you could always go find an unclaimed island and create your own country. At some point the practical impediments are such that yes, we are at their mercy. And no, Google at least does not deserve any gratitude for creating a more efficient ad delivery machine (what, you think they provide a browser out of the goodness of their hearts?).
You're not stuck in some evil country. You have Mozilla. If you want to improve it, you can submit code to it. Or start a new browser project by rounding up a dozen friends who feel the same way you do and going for it. If you're not a software engineer, you can be an evangelist who inspires software engineers. What is stopping you from working towards your own ideals?
And even if you could do it, it's not a given that you can make a good one.
In fact, I believe making a good browser is impossible because the web is fundamentally broken. The standards require your browser to be crap. The browser is no longer a user agent, it's a server agent, and trying to block & work around antifeatures is akin to writing an antivirus program that somehow detects and blocks malicious code without breaking the rest of the program. You can try, but it's a ridiculous never-ending cat and mouse game and if you don't keep up, you just end up "breaking the web" without actually making any part of it good.
We aren’t at anyone’s mercy.
Nobody is forcing us to use browsers from google or Mozilla.
We are all free to implement our own UA. The specs are all open standards.
What stops us from writing browsers is the sheer volume of time and effort required - hundreds of thousands of hours of highly skilled work. That is all.
In the absence of such an effort, we would be left high and dry, with no way to experience the web.
Fortunately, that isn’t the case, because some others have done the work and allow us to use their browsers.
For that, we might feel grateful.
We might also be wary, and try to be aware of any adverse consequences of using someone else’s thing. That’s common sense, but it is still not a case of being at someone’s mercy. That situation loomed when one company sought to control the standards for the web as well as the implementation, but what we have today is different to that.