It is always funny to see "professional" code or tools compared with "toys". In reality, it is precisely the "professional", "enterprise" stuff that turns out to be a giant pile of shit (which we rarely get to see from outside). There are professional businesses storing their main database in Excel, while the amateurs obsess over whether Postgres is scalable enough.
I would hope nobody is using it for anything professional now but it was definitely used back in the day, my first professional development job was for a small agency which used Dreamweaver for everything. I'm not saying that was a good thing, it generated some of the worst code I've ever seen, but it was used.
While you are correct that few are using it to build "professional" sites, it was never really a toy. Pretty powerful for the time, and even let you integrate with a number of backend technologies, database servers, etc. For today's world, where you need 3000 Javascript packages to display "Hello World", it's not a good fit.