I'm old enough to remember when Opera supported userscripts by default. I thought they were the future, but today it seems most would-be userscripts are just turned into extensions instead. Now that browsers have more granular permissions control, from a user perspective, I suppose it doesn't matter much whether it's called an extension or a userscript. But from a developer perspective it makes it's a little more tough to build a simple thing and throw it out into the world.

It's much easier to write a userscript than an extension -- the problem is distribution: almost no one know what they are or how to install them, etc.

But I have been making them at work to bypass and improve some quirks of Atlassian products for instance (JIRA and Confluence), and there they spread like wildfire.

I wrote userscripts to speed up annoying MS and okta logins, like the ones where you have to click to send a 2FA text or click a stupid checkbox to stay logged in. I also wrote one to show what I call "spending cash available" (cash minus credit card balances) on personalcapital. Plus I found one that turns youtube shorts into normal videos. Fun stuff.