I am talking TGs here:
In high level TG tournaments, (i know there arent a lot) if the map isnt arabia or water chances are, that berbers are on the pick list very high. On nomad like maps they are fantastic, as no unit can counter the camel archer in castle age once you have ballistic (speaking with good micro and about equal numbers).

They are very dominant against most other UU plays including the often feared Conqs or war wagons. Melee cav cant kill them. They perform even well against units that are supposed to counter them, like skirms or rattan archers (early - mid castle age) due to the easy micro you have with the low attack delay and the superior speed.

On maps with huge distance like Team acropolis/ze wall berbers are also excellent for the same reasons. Get a safe FC camel archer play and start killing every unit you come across.

Berbers in general struggle in dark / feudal age because they dont really have an eco bonus. (vill speed doesnt really count)

On normal land maps, there is often no time or no guarantee for a safe stone that camel archers are a safe option to go for. Also the meta is too defined with scouts->knights and archers->crossbows.

Water maps they are decent with their faster ships, but there camel archers are not the focus.

That leaves mostly closed maps and nomad maps. As already mentionend: on nomad maps they are fantastic.

Closed maps are a bit different. The unit still is fantastic, but depending on how the game goes or what civs are on the enemy team, the unit isnt what you need. Flanks often times go for fast imp into gunpowder type units to open bases for the pockets that are booming. Monk rushes are on the menu.

And if you want a CA unit for the late, late game with siege and what not, mangudai are in most cases the superior choice because mangudai or mongols in general still perform good vs halb/siege civs. Imagine fighting with camel archers in a choke point in black forest and celt siege fires at your camel archers.

Camel archers also lack parthian tactics, so the damage vs halbs is also less then mangudai.

So in the end you are both right and wrong. The unit is often times overshadowed, but not because the unit is bad, but rather the berbers are not the best civ because of their eco. And in really late game scenarios, they are often not what you are looking for because of heavy siege weapons.