Right up there with over seasoning food is under seasoning it. There’s a kind of cultural aversion to salt these days, which, combined with the general laziness toward tasting, results in blandness.
I try to teach people that salt isn’t for making food taste salty, but to enhance the existing flavours and to bring them into focus. Acids are another key component in this. If the salt and acid balance isn’t right, food doesn’t taste like itself. It doesn’t taste like much.
All cooks need to learn to identify the flatness / blandness / emptiness of unseasoned food, and to figure out the right remedy. This requires tasting and experimenting. Keep salt, vinegars, and citrus juices handy by the stove.