Yes, exactly. Aren't the followers usually NPC classes with the commoner (not even elite) stats array? That means their best stat is something like a 13. These NPCs would suck at anything combat-oriented.
I have 3 followers, level 1 experts, and they are all maxed out for Craft: Alchemy. Assuming a standard distribution of d20 rolls (1 to 20 in fairly even amounts), the three of them "churn out" a whopping 2 flasks of Alchemist's Fire a week. A week! Of course that's an average. When they roll well, they get one out the door every 2 days. But when they roll badly, it's a lost week, no progress.
Well, there's some problems there (beyond that fact that, as experts, they shouldn't be able to make alchemist's fire at all, since crafting that item requires that you be a spellcaster).
As Runestar noted, there's nothing in the Leadership description saying that your characters have the non-elite array, or NPC class levels. So if your followers were three 1st-level wizards, with maximum ranks in Craft (alchemy), a 16 Intelligence (+3) bonus, and took the Skill Focus (Craft (alchemy)) feat, they'd have a +10 bonus to Craft (alchemy) checks.
Moreover, they don't need to take a "standard distribution" of rolls, since they can take 10 on a Craft check. Doing so means that they achieve a 20, which is the DC to create a flask of alchemist's fire - moreover, that result multiplied by the DC to create the item is 400; double the price of the item in silver pieces (200 sp), which means it'd take each follower just half-a-week to make one flask.
This doesn't seem like such a big deal, but there is potential for problems, particularly if the PC here is inclined to screw with game-world economics. After all, it just costs one-third of an item's listed price to craft it, and you can sell it for one-half the listed price, meaning you always turn a profit.
By itself, that's still not too big a deal, but now add in those mages selling spellcasting services (being 1st-level characters, they make 5 gp per 0-level spell and 10 gp per 1st-level spell), and that's more money coming in.
Again, that's pretty meaningless, but it's just an example of what can be done. There's a great article in the latest
Knights of the Dinner Table (#146, I think) about maximizing character profit, and reselling is a big part of that. With several NPCs doing it for you, it can quickly get cumbersome for the DM.
My point is that (in my experience), followers are a burden - either for the DM (as they carry out myriad nickel and dime tasks) or the PC (babysitting them to keep them alive when the DM has a monster target them).