Because a lot of people don't have the technical ability. The tab is called "Advanced" for a reason.
It quickly gets more complicated for some sites, which users might use often. There are folks talking about how you can use custom CSS to fix just about any site, and that's true, but how technical are we expecting users to be?
And even as a user who develops websites for a living and can definitely do all this, I don't want to. The web should be designed to work for users by default. I shouldn't have to fix websites to use them.
> Because a lot of people don't have the technical ability. The tab is called "Advanced" for a reason.
Come now, it doesn’t take any technical ability to use the checkbox. It’s called “Advanced” because it’s more complex tweaks that most people aren’t interested in and which take a moderate amount of space so they want to keep it out of the way lest the page get too long, not because it’s hard to use in any way.
> It quickly gets more complicated for some sites, which users might use often.
It is rare for this to have any ill effect on any site (icon fonts that don’t use the PUA and aren’t Material Icons (for which Firefox has manual exceptions in place) are about the only case, and they’re distinctly rare nowadays—I only recall encountering about two cases last year, both of which were paired with labels and thus unimportant), and in those rare cases it’s unusual for it to be a real problem (they’ll almost always have labels or tooltips).
I will quite happily recommend changing this setting to completely untechnical users. It occasionally causes very mild harm, and can theoretically cause great harm for particular sites (but I haven’t found such a site for years, and any such sites were surely already broken anyway), but the rest of the time it improves matters markedly.
> Come now, it doesn’t take any technical ability to use the checkbox.
It's clear that you don't interact with average users very often if you think this.
Obviously you can direct the user through to the steps to check/uncheck a textbox, but understanding what that checkbox actually does and why they might want to check/uncheck it is far beyond the technical understanding of most users.
This is completely false. Both use images for the board and pieces, so you can play just fine.
Both do use icon fonts for some of their additional controls on the right hand side, but they all have tooltips so that you can identify them even without the icons. Chess.com uses a bad icon font that uses non-PUA code points (e.g. V = New Game, , = Move Back, … = Move Forward, g = Show Hint), so those ones will be broken. lichess.org uses PUA code points (except for “½” for “Offer draw”), so I think that those icons would even be loaded if you weren’t like me in just blocking web fonts outright.
