Earlier quoted context omitted.
Nearly half isn't enough to trigger antitrust. Especially because that nearly half is only mom and pop shops and not the ones doing the real big business. So I wouldn't be too worried about that.
Mom and pop are the consumers/victims here. And if 46% of all websites are WordPress, it’s probably likely that it has a monopoly on sites in its domain (e.g. blogging, commerce)
For competitors, on the small scale side, you have Wix/Squarespaxe/Weebly. Or just Shopify for e-commerce. For enterprise, Adobe experience manager is huge. Loads of places just write their own website and have their own CMS solution.
So no, it doesn’t even come close to having a monopoly on anything. And even if WordPress did, no individual company does. There are a huge number of different companies competing in the WordPress hosting space. Automattic doesn’t even host that much (https://w3techs.com/technologies/details/ho-automattic)