As if they needed to check for ""compatibility"" at all - just let the users try their makeshift coded-in-a-weekend browsers, or their 2008 version of IE.
The better question is why some websites even bother checking for the browser when the vast majority of people uses mainstream options that follow web standards and self-update.
Checking the browser version kind of made sense 15 years ago when updating the browser depended on the user's awareness and willingness of doing so, and the lack of standards across browsers was blatant. Nowadays that's pretty much useless. The maximum these sites should be doing is displaying a banner letting the user know their browser might be incompatible (because it's likely not in a way that prevents usage), then fuck off.
Companies like chrome because it’s the most used browser. So if they develop for it, and only for it without caring of compatibility on others, then it’s cheaper. And since they don’t want you to use another browser and complain that their site is broken, the just block you.
I found a bug once in our content that only affected Firefox. Old versions of articulate whouldnt start properly. Not somthing I could fix on my own as i meeded anyoher department. I brought it to the attention of the managers. They didn't want to fox it as apprently Google analytics showed only .4% of our user base was using Firefox. I manged to convince them its part of our user commitment to ensure that we work consistently across all browsers, but it was a pain.
On the desktop, Firefox has about 6% marketshare, and Edge, the Windows default, about 11%.
On mobile, however, Firefox is at 0.5%, and Edge at 0.3%.
A lot of people only browse the Web on a mobile platform. And the ones using those tend to use the default browser bundled with their phone; if what they have out-of-box works, they're not going to install anything else. Apple bundles Safari, and Google bundles Chrome, so that's what gets used.
I absolutely hate this. Ordered something last night that refused to work on Firefox or Firefox based browsers. Switched to my emergency Fulguris and checkout worked like police working for a white rich man.
What really chaps my ass is when they don't bother to tell you. It always happens when I'm filling out a form and find out that the submit button just doesn't do anything. Then I have to go back through chrome just to fill out the same form a second time.
The really irritating part is that tools like Playwright let you end-to-end test your product across the big three (Chromium, Firefox and Webkit). Which, most of the time, means these products that specify "Chrome only" simply aren't E2E testing with modern tools.
Because Google Chrome setups a good framework from the moment you open it to track, collect data, basically free market your internet life. Companies like to work the less possible using the least money, if Google already gives them all that setup for a fee then it's more profitable than having to pay programmers to track you in other browsers.
So they deliberately are saying to your face: "I only let you use my stuff if you enter as naked as possible". They are not even shy about it.
Someone like this only deserves a spit in the face and a domain ban. Basically. They can fuck off.
Notes: Most of what I said is not exactly all the true. Most companies just reuse webpage code that it's only tested form chromium, so they only let you use that. Because they are lazy AF, they don't care about customers, they only care about money.
Chrome implements features that aren't standards track into their browser, and lazy/oblivious devs use these features to build their products - only to realize wayyy too late it won't work in Safari/Firefox because it uses APIs that are chrome only