Level gating is fine in itself, but it needs to match the players' pace, especially early on. In a 'perfect game', the unlocks happen right as, or just before, a player has run the full course of their current tier. Tuning that takes effort, playtesting, and being open to suggestions.
What's not fine is when the level gating holds back players ready to advance. 7DTD is not a curated, level-based experience. The zombies you face now are the same zombies you face later. You cut your teeth on the real deal and it goes uphill from here. In that environment, the priority is to hit the ground running.
And so in A17, we hit the ground running. By around level 5, you probably *really* hate the stone axe for all the things it does; everything badly. I usually hit level 5 by day 3. By then, I've ID'ed a reasonable base location and established a stash. Then the scavenging for food, loot, and resources starts in earnest. Only.. you can't 'resource'. Your tool is the worst thing this side of the moon, if the moon was made of ass.
Levels 5-10 is then spent suffering the indignity of a tool fit for 20th century BC cave hobos while you try to prepare for high school prom. That takes prep. That takes stone and metal and wood. The stone axe is NOT up to that task, and you can't count on RNJesus to save your ass.
Sure, you may get lucky and find some tools. You may even find something to repair them with, but it's not consistent. Level 10 hits, you really want to get this show rolling, but lo.. you still have that ever so effective (as birth control) stone axe and still 10 more levels before the game actually starts.