IMO, it's not that hard to find units with different class. But finding *5 units with different class, yes that's a different story.
But that's where the strategy aspect of this game plays out. You need to utilize your available resources. And that way, newbie will be more focused to improve their current heroes before stepping on the Arena while waiting to get their lineups ready.
I also use hero like Dante Leon and Theia till Silver rank during early days. Heck, one of my friend even used *2 Boar creep to fill his champion slot. And now we managed to reach master tier just fine without using the same class on our lineups. And i believe the rng needed to get at least *4 units with 5 different class is not as bad as you implied in the first place.
Lets take an example shall we.
A person has 2 cybellas, a kane, a vincent, and a shizu.
But you cant use the same classes.
So the only heroes eligible are 1 bella/kane, 1 vincent, and 1 shizu.
If that person were to use the best of his resource he can reach top 20 easily. But since theres a restriction. He can only use his vincent, shizu and his bella or kane.
He doesnt have anything else other than those heroes besides some trash *3/*4.
Because of that he can only get to top 100.
Now. You see my point? He has the resource but the system hold him back.
So unless youre lucky with having different classes, people that spends will be having a lot greater advantage (since they will be having more chances on having different classes of heroes) than our situation now.
ALL TO NERF ARCHER.
And shortly after people will ask to release the restriction cause of how stupid it is in the first place
addition:
Impractical combo, 30% chance wl + 75% chance mb, good luck. Not to mention wl's skill to pull is useless considering you can 1 shot with zerk's skill, also the crazy buff AND the buff he gives to other heroes on his aura.
Btw nice job on winning against zerk AI, they really shows how zerk is utilized.