So this is where we have to look at the notion that “not all levels are created equal”.
your point is true at 1st level, but 1st level is intentionally designed to be moved through quickly, and many games start at higher levels.
Then from levels 2-7 the monk has lower AC. This is the “sweet spot” of gaming, the vast majority of games and tables are playing in this level range.
then at 8th level the monk equalizes (assuming specific stat bumps...and the fighter is not taking feats that boost AC...which is generally a reasonable if not rigid assumption). However for many campaigns this is epilogue time...the game is starting to wind down.
So for the vast majority of “screen time” at the table, the monk has worse AC.