This is precisely why you will never reach the level of a top player.

The real game usually begins after the first finale; everything before that is just completing homework. On Jebus Cross and similar templates, the game typically ends at the first finale.

The ability to fight neutrals and build chains to collect goodies is the simplest part of the skill set, something many can master. The ability to fight an opponent is a more complex aspect, mastered by few — I occasionally watch streams, and most finales induce boredom due to the sheer number of mutual mistakes. Even harder to master is the ability to maneuver on the map in the late game — capturing and holding territory, distributing forces across different areas of the map, catching enemy weaklings and the main army, intercepting reinforcements, etc. And the most masterful skill is the ability to come back from bad positions. Lost the finale in the 2nd or 3rd week? No big deal, we'll bring in the endgame.

Everything you're talking about happens regularly on all other templates. Usually, the game doesn't end with a single major encounter, or what you call a finale. That's when everything you described actually begins.
Take Jebus Cross for example — there was a game recently where I reached the center on day 123, my opponent (red) on day 122, he caught me on day 124, I preemptively bribed (bought back my army), and he took out my main stacks. Then, knowing I couldn't win yet, I went back to the center and to a nearby respawn. Long wars of scouts and small armies ensued while the main army recovered. In the end, it dragged on until week 4, when I finally pulled it off. And this happens in almost every 2nd game; if players give up immediately after one lost encounter, that just shows they have weak willpower and no character. It's a different story if there truly are no prospects — then it's time to surrender. But you should always try to find them and fight to the end. Wearing down the opponent's nerves is a very useful psychological tactic in Heroes, and you yourself know just how effective it is.

Well, and yes, it depends on what each person considers the level of top players. You're probably only judging by games on 8mm6a and on WT.