There may be "plenty" of other competitors, but I think it's pretty undeniable that Figma is the "up-and-coming" (or maybe it already got there) market leader among "design tools for web design". I also think it's pretty apparent that Adobe knows this and that's why they want to buy them.

This is the exact same pattern as Facebook buying Instagram, and heck the same as some of Adobe's previous acquisitions, where large corporations buy out competitors that could potentially overtake them.

If antitrust means anything it should block these types of acquisitions.