This will certainly affect adoption. Forcing an open standard into a closed system seems intuitively wrong.
But at least kudos to Apple for recognizing the need for webextensions support.
It dips its toe in the water. It then eases an ankle in. It finally jumps in fully when it's ready to, and not before.
Along the way, the sort of developers who spend more time posting on Twitter and HN than actually developing complain about each of the first two steps being not enough, and when the third comes moan about "monopoly" this and "lock-in" that.
Apple isn't going to make everyone happy. And it doesn't care to. It brings what it feels its customers want. But it is rarely rushed to something because it's cool or trendy. Apple gets there when it is ready. The times when it has rushed, it's botched the job. So I'm OK with Apple's measured approach.
If what Apple offers you today in Safari isn't what you want, go Firefox.
[0] I know they force all browsers to use the same webkit engine as Safari on mobile devices, and used to limit competitors to an older slower version for “security reasons” but AFAIK they don’t slow down competitors on mobile anymore and never have on Macs
Chrome has a similar extension but it's nice having it built in to the browser natively.
If anything you could argue that FF is behind Chrome security-wise with their more limited sandboxing and some other memory protections. But performance is largely a non-issue.
When comparing apples to apples, Firefox imho is actually lighter than Chrome on battery, at least on Macs.
In my experience, Safari slows down to a crawl if I open more than 5 or 6 tabs at once, especially something sadness inducing (think new reddit); and it's very eager to.. dump things from memory? I am not sure what happens, but as I switch these gargantuan tabs, it seems to re-draw things a lot.
Firefox handles that kind of thing like a champ. Add uBlock origin, and I have my almost ultimate browsing experience: JavaScript off default, enabled as I see fit.
There is one nasty oddity where I often found myself having to slow down for Safari: when I edit URL query parameters. If I hit return before some indecipherable arbitrary time, which I guesstimate by the auto completions showing up, Safari will throw away my changes and merely reload the current page. I have unchecked and toggled all possible autofill or search checkboxes in Safari settings, and it still happens. This and the extension apocalypse are what drove me away from Safari. In contrast, I've got all the extensions I want, and never ever have to slow down for Firefox.
Well worth giving it a shot for a few weeks. Container tabs are also awesome.
I use Firefox on Mac, but it is definitely a compromise. Still no multitouch support, which is crazy in 2020.