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

[BakaWakka]

Again and again, DESIGN FLAW NOT PROFFESION FLAW.

I find it interesting that instead of addressing the blatant flaws that summoners have, you're instead pointing fingers at the content and saying that all the content is flawed. Almost as if you think the entire game should be centered around summoners when every other job currently has no issues at all with the current content. Interesting indeed.

At the end of the day, numbers are numbers, and Summoners simply cannot keep up with Black Mages in the current content, and their "utility" is next to irrelevant.

But then again, according to you, Square Enix should change all content in the game so that Summoner is more useful, rather than simply, I don't know, changing the class itself.

Interesting argument indeed.