>>26881253See, but Mega fixes the problem in a unique way. Early obtained and evolved Pokemon should be weaker than more arcane, laboriously raised Pokemon, and it's important that you have that distinction. However, Mega stones are often obtained later or are somehow difficult to obtain, making that next power level justified.
Having the base evo being stronger doesn't encourage players to catch new Pokemon. This is one of the biggest advantages of Megas, and one that's often overlooked.