Anytime I search for an addon via the search box in settings > add-ons manager I get all these theme results. Here is a search for "syntax" (via the add-ons manager) I had to make it very zoomed-out to fit long page into screen cap:
I use themes personally to visually differentiate between profiles. And I have nothing against fun and frivolous user customizations. Am not hating on the concept.
I am curious about why they are so aggressively pushed so that they show up be default when trying to search for add ons you need to toggle off every time. Searching for an add-on to do something and searching for a theme that has some keyword included seem to me like totally different tasks and mixing them up is a strange choice.
Is this like a major things firefox thinks people like about it? Do people like it?
I feel like it's just a matter of it being easy enough to scroll by. Most people don't regularly install add-ons or themes, and will never get too familiar with the UI to know to select one or the other, nor will they be annoyed by having to scroll past themes.
Plus, you might search for an add-on, but randomly scroll past a cool theme and because themes are so easily digestible, you'll immediately know that you want it or not.
Which isn't to say, I'm completely foreign to your pain. I prefer to keep the unpersonalized OS aesthetic, so even a cool theme wouldn't get installed by me. Albeit, I haven't gotten annoyed enough by it so far.
Having said that, if you install add-ons that often, maybe you'd like to add a custom search bookmark.
Use this as the URL to only see extensions:
I did that a while ago but I never remember to use it :(