Hm. I've been in the practice of figuring out plain old URLs to use as hrefs for social share. No JS. No loading of images or other content from the third party social network.

This, when it is doable, of course provides no tracking (until/unless a user clicks the share button anyway) with no need for "two clicks" -- the remote site receives no network traffic at all unless you click the button, it's just an ordinary static link.

I have generally been able to figure this out for major social network sites, either from documentation, third-party documentation, or watching HTTP requests made by the 'official' JS solution. I guess it's possible it violates the "ToS" of the remote site to do this, although I'm not sure ToS can really restrict my linking to the site with a URL. I guess this technique could be more subject to breakage, if the remote site changes it's URL patterns, and the "official" (JS/tracking) solution from the remote site is updated, but I'm not using that.

So there are potential downsides -- but I'm curious which of them (or something I'm not thinking of) leads people to a more complex (and slightly worse UX) solution like this, instead of just using static URLs.