Indeed.

I've seen two AS/400 via Telnet(-like) systems replaced with a modern GUI (first case) and a web based GUI (second case) and aside from all the usual problems associated with an en masse migration they ended up been far slower for the end user.

TUI's with complete keyboard shortcuts are just hard to beat for domain specific software.

Things like "Click Orders - Click Open - Click Create New Order" vs SHIFT+F9.

The other thing is that once your users have learnt the shortcuts they become internalised and they don't even think about them anymore.

I've seen developers where you'd need crowbars and grease to seperate them from vim advocating for replacing a TUI with a web GUI.

That one did make me giggle from the sheer level of irony.