The "comply with the license" part is the problem you're not seeing, using open source as SaaS is a loophole not a license feature.

An example being, I license something as open source which means if you don't pay for it (assuming there's an option for that), you are bound to follow the license I provided which means all further work has to be open source (the same license I used) and source has to be provided with the product. In an ideal world this would mean either:

1. We both get paid

2. We both contribute to open software which is available to anyone

But in our world it means, technically I'm not selling software but a service so I don't have to do shit. so the result (with scummy companies) is the following:

1. I don't get paid for software critical to your business

2. No one gets the benefit of the new product created despite my license

Hence, scum.