Going to cross-post from another thread because I think the role of TC20 is largely based on how much one spends & how much one summons:
When you spend many $$$ on summons, the whole of TC20 is unnecessary… Or when you’re a REALLY late game F2P or C2P player & have heaps of unlevelled 5* heroes…
If however you are new or a C2P or F2P player, you probably RELY on the TC20 for most of your 5* heroes… So for those players, TC20 is absolutely necessary.