I don't know what 96 vCPUs means in terms of real cores, and my server knowledge is a bit old at this point, but here goes.
There's a benefit to running on fewer servers. If you can make good use of many core machines and gobs of ram, it makes sense to go up to at least reasonably large machines. For Intel, dual socket Xeon is widely available and not obscenely priced; for AMD, I haven't seen a lot of dual socket Epyc, but 64 cores in a single socket is quite a lot. 768 GB seems big, but if you can put it into one machine instead of 12 machines with 64 GB, that helps reduce maintenance and communications overhead.
I ran systems with dual Intel Xeon 2690v4, a total of 28 cores/56 threads, and we put up to 768GB in some of them; that was several years ago, you can get a lot bigger now.
Databases love ram, and social sites make a lot of queries, so it makes sense a bit. I don't know what their usage numbers are, or what their site looks like; I'm just guessing based on general description. The traffic numbers didn't look too big, but types of request makes a big difference there; serving media is relatively easy, serving comments threads and highlighting your friends is trickier.
(Serving media with transcoding is a lot less easy though)
There's a benefit to running on fewer servers. If you can make good use of many core machines and gobs of ram, it makes sense to go up to at least reasonably large machines. For Intel, dual socket Xeon is widely available and not obscenely priced; for AMD, I haven't seen a lot of dual socket Epyc, but 64 cores in a single socket is quite a lot. 768 GB seems big, but if you can put it into one machine instead of 12 machines with 64 GB, that helps reduce maintenance and communications overhead.
I ran systems with dual Intel Xeon 2690v4, a total of 28 cores/56 threads, and we put up to 768GB in some of them; that was several years ago, you can get a lot bigger now.
Databases love ram, and social sites make a lot of queries, so it makes sense a bit. I don't know what their usage numbers are, or what their site looks like; I'm just guessing based on general description. The traffic numbers didn't look too big, but types of request makes a big difference there; serving media is relatively easy, serving comments threads and highlighting your friends is trickier.
(Serving media with transcoding is a lot less easy though)