[toyg]

> developers still walled their websites with useragent checks

Opera was, I think, the first browser to make UA-switching a first-class feature, precisely to avoid this phenomenon. I believe at one point they even sent a fake UA string by default. This sort of thing was really not the reason they hit the rocks.

The truth is that making a browser is hard work for little reward. Keeping up with web standard was pretty hard already, for an operation running on thin margins and based in an expensive country; when Google got in the game, brutally accelerating the development of features and hammering people with adverts for Chrome, Opera struggled to compete. They found some margins in the developing world, where their bandwidth-optimizing services were popular; but targeting the low end of the market only buys you some time (if you exist because connections are bad, as connections improve people will leave you).

Eventually, their perennial search for cash ended with an inevitable sale to this or that financial shark, and here we are.

[Ndymium]

> I believe at one point they even sent a fake UA string by default.

In fact Vivaldi, the spiritual successor to Opera, just moved to a fake UA string in the latest version (masquerading as Chrome), precisely due to UA sniffing still being a thing, even with Google's sites.