Honestly they were so far ahead of their time that they still more than hold their own today. Nothing remotely came close to the D800 for years for resolution, and some only came close on dynamic range. Sure AF got better (it's still decent though) and dynamic range only slightly better in the last 7 years but many working photographers still use them and use them well.
For what I do the only 35mm format cameras that are better than the D800 are the D810 (just), the D850, Z7 and the A7RII and A7RIII from a sensor resolution and dynamic range point of view. There's a lot of newer 35mm format bodies that cost more that I'd rather not have over a D800 ( eg a 5d4, 5d3, Z6, D750, A9) etc etc.
The only gripe I have with the D800 is the hand grip being shallower than the D810. The D810 is just an improved D800 and I really like them both. Strangely I find the D810 less useful at higher ISO than the D800 but it's slightly cleaner at base ISO.
The D800 was such an insanely good camera that it has stood the test of time almost like no other.