Ask HN: Why are SaaS companies seen as more attractive to work for?

I've seen on a lot of Who's hiring threads how companies say they have a SaaS product as a selling point, but for me it works like the opposite. As a FLOSS enthusiast, and excepting the very rare cases where the software offered as a service is fully open source, SaaS feels to me even worse than writing closed-source software.

However, I have to say my experience in software engineering is mostly on SaaS companies, so perhaps I'm just seeing the grass greener at the other side of the fence. Is there any huge advantage of SaaS companies I'm missing?