Most of the games do give you a strong character at the start (usually a paladin), but you're meantnto use themnas little as possible.

The reason for this is that these characters tend to be from a promoted class, which means they have less room to grow overall, as they have less potential level ups in the game. Theybalso tend to have sub-par growth rates in most stats, which means that by the end of the game they are demonstrably worse than another character of the same class who you brought from level 1.

The fact that they come pre-promotwd also means they get vastly less exp from killing early game enemies, which punishes you in the long run by having your other units end up underlevelled and much less capable.

These units are meant to be an oh shit button or a way to weaken enemies so that your weaker units can get killing blows and level up, and tend to fall off hard later on.

Seth from Sacred Stones is an exception. He is excellent and you can solo the game with him.