Cerner's CoPath Plus is written in PB and it's atrocious. I had to pull the CoPAth VM servers out of the DC because we needed to move them, and if the IPs changed, Cerner couldn't tell us what might happen. Literally I was told, "we don't support changing IP addresses, we don't know what would happen, we'd have to reinstall the application on new servers and move the data."
I asked how much that would cost. They said $25,000. For four VMs. The main app server, a DB server, and two webservers that serve reports to the outside world. $25k to reinstall the app we already paid for and pay a support contract for.
In the same way they'd hate bad apps written in any other framework.
PowerBuilder's honest biggest problem is that it was likely used by internal and consultant teams looking to quickly deliver value, sometimes to the detriment of solid architecture decisions. And that the resulting applications have been useful enough that people are still running them (without updates) a couple decades later.