Yes imagine if rdps rankings didn't exist, there's a decent chance overpowered jobs like black mage would be able to 'hide' how overtuned they are. People would look at black mage doing, for example, 16,000 pdps, and summoner with 13,000 pdps, and handwave it away with unscientific excuses like "Oh it's pdps, people probably like to pad black mages more" or "I bet devotion is actually worth 3000 dps (lol) so summoners are actually not behind". The only way people would notice is when high end speedrunning groups realize they're getting far faster clears with blm/mnk/drg comps and slowly everyone gravitates to that and people start noticing that trend. That would've taken months to sink in, now all that data is out in the open visible to everyone from day 1.
In that vein, I have to question how true the claim is that jobs like summoner were actually strong in Stormblood. Rdps rankings did not exist back then, so it's not like there's any numerical proof. Black mages were already doing more pdps than summoners in alphascape, and the actual choice to run with summoner was just, again, unscientific handwaving like "I bet devotion contributes more damage than the pdps advantage that blm has". If you look at the speedrun rankings for alphascape, since speed is the clearest indicator of rdps, you'll see that the top 5 runs for all fights all feature black mage in it. In fact, in some fights black mage is present in 4-5 of the top 5 rankings, so clearly it isn't as weak as some people claim.
Of course player perception is another story. It doesn't always match up with reality because information takes time to trickle down and influence behavior. A job can be strong but unpopular (HW ranged), or weak but popular (current ranged). Like I have said before, black mage was objectively balanced in alphascape, but also underplayed because the bad reputation they had from the start of the expansion took time to wear off. SE probably balances partially around the playrate numbers of the job, so seeing everyone abandon black mage probably led to the panic buffs and the current overpowered state of the job. Now the situation is reversed and summoner is in that position, and mark my words history will repeat itself again.