Out of curiosity Seriha could you elaborate a little about the "suck at them all" part? I never felt like that was the case in XI (Not sure how it is past 75). I mean it just feels like it depends on how you define roles.
Suck is a strong word but the idea isn't wrong. Yeah, RDMs weren't bad at anything, but in MMO terms "not bad" may was well be worthless when you could have "great" instead. RDMs were really great at a few specific things and decent at everything else. Decent is fine when you're solo but meaningless in a party setting when people want efficiency.
But RDMs can heal, nuke, melee, tank, etc, all with just a quick gear swap! Yeah, but did anyone actually let you do any of those things? I spent a lot of years as a 75 RDM and my memories mostly involve main heal or GTFO. In a party I was there for cure, haste, refresh, sleep, and occasionally chainspell>stun. The only time I got to do other stuff was solo or messing around in small groups.
Slow to get back for the reply, but Karlina basically covered it. The MMO meta doesn't really want 2nd or 3rd string anything when the 1st rate options are available. This point is further emphasized when a given piece of content limits your party size for whatever reason. How things fall in the pecking order is something you'd further have to math down. 5% difference? Probably not so bad. 30% difference or more? Yeah, get out.
Something I frequently encountered back in the day while clamoring for buffs to melee game were people who felt the class would become both OP and that no on would ever play anything else. Now, buffs is a broad term, and I'd even broken down the weaknesses of RDM's melee game into multiple points at that time. Things like gear availability (including inventory restrictions), WS access, food options, TP feed, unique benefits, and then some were all facets I tried to approach the argument from. Some counters simply came from embittered WHMs angry about RDMs stealing their role as healer. Some came from RDMs themselves who didn't want to have to get new gear or (re)learn the job to play it to a new standard. Others were just plain stuck in that zone of irrationality where just because they couldn't see it working, no one else must be able to. Oh, and because some people poopsocked some HNMs, we weren't allowed nice things, either.
In the end, XI's RDM was in somewhat of an awkward place, in part due to gear swapping being a thing. My ultimate take is that if you wanted to melee, subbing WAR or NIN should've been enough with the right gear. Want to heal? /WHM and /SCH. Nuke? /BLM and /SCH, or heck, maybe even /DRK for Stun. But the reality of XI's RDM is that it wound up more mage-heavy as time progressed while playing healer was a low-gear demand side. After all, the expectation was that all you had to do was ride Refresh and Convert, nevermind the other aspect of the equation that involved your party both mitigating damage well and killing mobs in a timely manner. If they failed at that, even the best RDM would eventually run dry. RDM was perhaps "the job" everyone knew how to play, but few wanted to. Why? Well, arguably because a lot of other jobs were more fun and less stress. SE eventually building "better" RDMs through BLU, DNC, and SCH is just a proverbial twist of the dagger.