The same people who run Hypixel minecraft server?

They didn't just "maintain" a server.

They developed custom mods and solutions, over 40+ minigames, custom plugins. Like I said, its more of a "custom experience".

It is this knowledge, not "maintaining a server", which is the precursor to starting a whole new game.

For example, Icefrog was involved in the creation of the original DotA gamemode for WC3. Valve, 10 years later, hired him when they were working on DotA2. It was not his experience running a custom game mode in WC3 for this hiring - it was the custom experience he helped create