If all you've done is played 2 levels of fighter and never engaged with Most of the mechanics and gameplay of even low level D&D, you are still a newbie.But you have two levels of fighter before you even get to Champion. By the time the newbie is playing a Champion she should no longer be a newbie.
No, it is. The Champion adds but a single weapon damage die of damage over 20 attacks and at best +1 AC for the majority of the levels people play.And an optimized Champion is not "hilariously weak" in tier 1-2, where most of the game is played, it is above average as far as non-casters.
It is hilariously weak. Action Surge is doing the heavy lifting. And AS alone is not enough to remain equal to or surpass noncaster warriors.
That's why it is hard for even newbies who pay attention to see the weakness of the Champion IF there is another warrior of similar optimization to compare themselves to. Unless the DM uses a playstyle that accentuates the Champion.
Barbarian? Maybe the bad subclasses.Assuming equal and average ability scores; most Barbarians, all Monks and most Rogues are mechanically weaker in combat at most levels from 3-10. That covers at least half of the possible non-caster builds
Monk? I forget. Is the monk a good or bad class again.
Rogue? The 5e Rogue was not designed to be a warrior.
Notice you didn't mention the Ranger, Paladin, or any other Fighter subclass. Even some warrior subclasses of other classes can outside the Champion effortlessly.
Which goes to the point that point that the Champion goes unnoticed as weak if they have nothing to compare themselves to or are favored by the DM.
Because WOTC only gave it one class feature slot to built the archetype with. Whereas every other class and every other subclass was given multiple levels. It shows that originally 5e was going to be shelved by WOTC.