Why do some games have casters, while others just a graph?
There are two MOBA engines, which are enabled in different scenarios:
The "new" engine:
The new MOBA engine (Camus) is a live representation of a MOBA game, with casters (live commentary) and players communicating.
This engine is enabled in Matchmaking (Ranked, Quick Matches, Friendly Matches), and soon will be enabled in official tournaments.
The "old" engine:
The "old" MOBA engine (Beta) is a simpler and more "opaque" engine that doesn't run live. It's only enabled as a backup when Camus is not available/enabled.
Is there a champion tier list?
There is no official champion tier list, but you can count of the community to have one (or a hundred).
Is MOBA (in ESMO) related to League of Legends or Dota?
No. MOBA in ESMO is an independent game mode and is not affiliated with, endorsed by, or a representation of League of Legends, Dota, or any other existing MOBA title.