If you google "supermicro 72 drive server" it's definitely a thing that exists, but these use double-length drive trays where each tray contains two drives. Meaning that you need a "whole machine can go down" software architecture of redundancy at a very large scale to make these useful, since pulling one tray to replace a drive will take two drives offline. More realistically the normal version of the same supermicro chassis which has 1 drive per tray is 36 drives in 1 server.
There are other less publicly well known things with 72 to 96 drive trays in a single 'server' which are manufactured by taiwanese OEMs for large scale operators. The supermicro is just the best visual example I can think of right now with a well laid out marketing webpage.
You don't LEGO assemble rackmount servers. Chassis come with figurative array of jet engines with 12V/0.84A -ish fans that generate characteristic ecstatic harmony. They're designed, supposedly, to take 35C air to keep drives in front at 40C and GPUs at back <95C.
There are other less publicly well known things with 72 to 96 drive trays in a single 'server' which are manufactured by taiwanese OEMs for large scale operators. The supermicro is just the best visual example I can think of right now with a well laid out marketing webpage.
edit: some photos
https://www.servethehome.com/supermicro-ssg-6047r-e1r72l-72x...