System requirements for Rocketchat server so high

Description

Why are the system requirements for Rocketchat server so high?

This is the sizing guide from Rocketchat page:

Based on this hardware specifications, for 1000 to 2000 users (Small HA - Monolithic), it requires 30 CPUs to 60 CPUs. Why is such a high number of CPUs needed when VPS 0-500 users require only 0.8-3 CPUs, and is there any formula or criteria are used for this calculation?

Could I use less CPU for the same Total Users with isolated server environment like VPS?

I have the same question. My team and I are considering using Rocket.Chat or Mattermost.
The last thing I’m worried about is Hardware. The requirement of Rocket.Chat for Hardware in HA is very high.
I don’t know if the system will still be suitable when the system is scaled up.