Whenever people criticise Bethesda games for their engine, I pretty much assume right away they know nothing about game development. Bethesda's engine is something they have a lot of control over and can constantly improve and iterate on. It's not as though Starfield and Morrowind are running on the exact same codebase.

Starfield is bad because of bad game design, not bad game development. Skyrim was buggy on release as well, and yet people loved it because the design of the game was good enough that people were willing to forgive the programming flaws. People overvalue the engine in discussions about Bethesda games and it's become this meme among people to seem like they sound like they know what they're talking about, but ultimately the flaws in Bethesda games that determine their success has very little to do with what engine they use.

Also, the Skyblivion team is constantly releasing dev diaries showing the progress, and the mod is nearly finished. It looks very well done, and the whole thing is out in the open. There's no reason to be cynical about whether it will ever release when you can literally go look at the progress with your own eyes.