Yes and those X-Terminals were exactly what X was invented for. This is why the net transparency is not great over high-latency connections, it was never designed for that. In those days companies only had a handful of "computers" and people worked on terminals. Usually shared over a 10 megabit shared ethernet bus, which was surprisingly responsive!
However they were more than a simple terminal. Most of them were basically small Unix computers (like the SPARC X-terminal which was just a diskless low-powered SPARCstation, it could actually run full Solaris). HP's EnvizeX stuff was similarly complex though I don't think they could run HP-UX. But they weren't nearly as 'dumb' as the text terminals of the days.
I still have a few Sun Rays here but they used a very different protocol that only worked with their proprietary software.
However I do expect a return of this model. Now with the cloud, a lot of computing is once again shifting to a central model rather than on the endpoint.
However they were more than a simple terminal. Most of them were basically small Unix computers (like the SPARC X-terminal which was just a diskless low-powered SPARCstation, it could actually run full Solaris). HP's EnvizeX stuff was similarly complex though I don't think they could run HP-UX. But they weren't nearly as 'dumb' as the text terminals of the days.
I still have a few Sun Rays here but they used a very different protocol that only worked with their proprietary software.
However I do expect a return of this model. Now with the cloud, a lot of computing is once again shifting to a central model rather than on the endpoint.