I believe the other person was talking about having the devices serve up webpage UIs, so you wouldn't need their specific app, just a browser. A lot of makers do this with their 3D printers and CNC machines, as it avoids the cost and hassle of installing a display on the machine.
Two of the more popular ones, for those interested:
Personally I don’t like those either. I’ve experienced it with printers (which can only be configured initially via USB and some app), 3D printers (configured by putting an SD card in your computer), and other gizmos. They’re all a pain to deal with, especially if your WiFi details change or their IP does.
Some others expect you to connect to THEIR Wi-Fi network instead. Which is also a complete pain.
I don’t mind having an app to make the device more useful, but it needs to have enough controls on the front to use the thing and preferably reconfigure the Wi-Fi if necessary.
At the time I was considering it, I figured there should be a dedicated protocol for serving things like this. Something simple, like a subset of bluetooth, with easy discoverability. Sort of like NFC perhaps. Something that you can implement with minimal software and hardware support. Obviously you risk the protocol dying and devices becoming bricks. I'm not sure how you avoid that.
Heck, we've even seen that model simply to use goods you've purchased, as with digital restrictions malignant books, music, videos, and games, where the restrictions-management servers were discontinued and access to the goods (bads) bought requiring them became useless.
3d printers and CNC machines almost always involve using a computer anyway and good chance they are physically connected. Not the case with my washing machine or toaster
Two of the more popular ones, for those interested:
octoprint.org
cnc.js.org