A lot of thin clients came out in the 1990s and they were garbage. Web browsers are ridiculously inefficient (10x or more cycles to draw similar UI), yet thin clients had something like 1/10th the performance and 1/4th the RAM so the net performance would be 20x-100x worse than a PC for 1/4th the price.

WebTV was kind of an exception to this; it was very fast due to the split browser architecture and putting very little content on the screen. IMO their amazing engineering was wasted on the low end of the market.

VNC/Sun Ray was a much better idea, but only within a LAN.