No, it's not true. There are no weapons that can't be found during normal gameplay or through crafting (although the set hats are difficult to craft or find, so the criticism is probably justified for those. Only the spy one is really significant though, and it's not gamebreaking). Once you start playing, you'll find weapons quickly enough. It's true, though, that you'll be waiting some time before you build up enough spare stuff to be able to craft specific items you want.
Most of the genuinely useful gear (Kritzkreig, Axtinguisher, Gunslinger, Sandvich and such), which really gives the class something new to do, can be earned from achievements. So you'll get them just by playing the class for a while, rather than have to wait for the random drop system to give you what you want. Or you can just farm the achievements, if you're really eager to get the weapons quickly. You won't be underpowered without them, although the axtinguisher's improvement over the fire axe is really significant. I wouldn't want to have to use the fire axe, but that's more an issue of the class than the weapon.