Can someone give me an in-depth explanation why Summoner is arguably the worst DPS?

[Akiza]

I don't know Akiza, I feel that 30 seconds would have a bigger impact than you are thinking. Even sneak attack with 500 potency is on a minute cool down. In a long fight like Bahamut not so bad, but the rest of the game.... I can picture running dungeons and dropping rouse/spur enkindle on large pulls for 500-600 potency per mob, every single pull. it would be more "summonerish", but that is a whole other conversation. We are currently not a nuke class and that would start us on that path.

If you take just the Summoner without taking into account the mage they're attached to it's a nuke class also Summoning Magic hits harder than Black Magic the trade off is they have poor mp management. Classes shouldn't be balanced around dungeons they should be balanced around the hardest content.

[Skeith-Adeline]

SMN doesn't hit harder than BLM either...?

[Viridiana]

SMN doesn't hit harder than BLM either...?

I assume he means in other FF games, where SMN gets the big mega-attacks that tend to be more powerful than even Flare.