For most of the reasons people shit on XIII they praise X. Both have a lot of the same problems from being too linear to a terrible plot and characters. Not to mention the godfucking awful Nomura art design strikes again.
I don't think is is necessarily true at all. While both are linear, FFX offers the ability to revisit old locations, especially since there is additional stuff for you to do. FF13 you can only go back to Chapter 11 and 12 (parts of only I believe).
While you could argue that FFX might not have a strong plot or characters, comparing that to FF13 is incredibly disingenuous. The plot in FFX is far more comprehensive, and far easier to keep track of. Story beats at least make sense, and character motivations (and their growth) do too, in part.
This is not the case in FF13. It presents a barebones story that is only fleshed out through pages and pages of encyclopedia entries. It also manages to be more difficult to follow due to the heavy use of in-game vocabulary that they somehow expect you to understand from the moment they are uttered. on top of this, most the cast are just completely flat with almost zero growth.
If you ask me, even if you consider FFX a weak entry, it's mile better in virtually every department to FF13.