Circa 2000 all of my "normie" relatives had 20 or 30 different "toolbars" installed in their browsers from the likes of Yahoo, Lycos, Hotmail, Infoseek, Altavista, etc. They had horrible 640x480 screens that were effectively 640x120 but they thought it was normal, didn't have a choice, etc.

When you install plugins into GUI applications they eventually die of "pluginitis" as something adds 0.2s of latency here and something else adds 0.3s and... wow, a race condition!

The cases I will install an extension are: (1) it is required for work, a project, whatever or (2) I expect it to improve, not reduce performance, such as an adblocker or anti-tracking tool.

It might seem like an anachronism, but I still make bookmarklets that do pretty fancy things such as to cue a personal webcrawler.

In some sense it's adversarial like trading/investing, people who have a working strategy can't share it or it won't work anymore.

But the bread-and-butter is probably setting it up correctly to facilitate word-of-mouth, influencers, ads in communities your users frequent.