In competitive Pokemon, Charizard isn’t really used anyway. But for other Pokemon like Volcarona, they don’t really suffer too much because of the item Heavy-Duty Boots, which denies entry hazards. So it does take up the item slot, but it doesn’t really hold you back too much. For Charizard, either put Heavy-Duty Boots on it or have a Rapid Spinner. Personally, I don’t think it’s held back too much.
For Charizard, no item slot is a huge loss though, because its stats can’t really deal too much damage compared to other meta Pokemon. I’d say for Charizard, the weakness does make it a bit worse, but it’s already not the best to begin with.