As you say, Sketch and Adobe XD are desktop apps for the sole designer. In Figma, no designer presence needed for a myriad of use cases and user types.
I can only assume in the future soon Adobe will change Figma sign-ups into Adobe ID accounts (like Adobe have done with Behance).
[1] The Sketch team wrote a blog post extolling the virtues of native apps - no doubt with a nod to their Figma cloud rival.
Why we’re proud to build a truly native Mac app (Oct 2020): https://www.sketch.com/blog/2020/10/26/part-of-your-world-wh...