Stegadon at least will give you a decent anti-artillery option along with melee beast.
normal stegadon in melee and lizardmen have better monster options than both anyway. Ancient stegadon is already considered expensive since its performance is not much better vs. Most of the time it gets talked down from what I’ve seen is regarding its use in multiplayer. It’s total war and the AI sucks, so yes, you can use anything your heart desires.) And for the record, I am talking about what is optimal in campaign meta at legendary difficulty.
Yes you can still get by with this in some situations but it will lose against many different factions and army types. (edit to avoid additional pushback: by mass melee infantry I am talking about 15+ melee infantry in one army. I would definitely bring 1 or 2 in my lizard armies just for fun. In general though campaign balance discussions are moot points since pretty much everything can work in campaign except massed melee infantry and flyer-only armies. both infantry and large targets, just not foot lords or fast, relatively small single entities. Normal stegadon is just typically considered better because it has artillery shot (something lizards otherwise lack outside of solar engines which just aren’t strong enough in melee to bring en masse late game) with high range and nice damage potential vs.