Also, there's something I think worth clarifying about the relationship between smn and blm and how welcome they are in raids. By and large, summoners doing high dps are not the reason black mages aren't taken to progression, the reason black mages aren't welcome in prog is because they don't have a raise. This may sound like I'm just saying the same thing in two different ways, but it's actually two separate issues.
The thing is, there is no amount of dps you can give a black mage that will make people bring it as the only caster to prog as long as they don't have a raise. That's just how good raise is. The first time my group got to see octet in ucob, it was because I managed to raise a healer who got to lb3. All because of 1 button press, we got valuable practice on a new phase instead of throwing 15 minutes of work away and staring at twintania again.
No amount of buffing black mage could allow them to pull that off. With SE's current fight design, access to raise is a qualitative advantage, while potency changes will always only have a quantitative effect.
Yeah, we had eden Titan week 1, but in many regards that was an outlier due to that fight being mechanically easy but numerically (tuning wise) difficult. It won't happen in ultimate, and I guarantee you groups that switched to blm to make the dps check still brought in rdm/smn for the learning pulls before they reached the enrage. As long as raise exists, you will never escape the need to know how to play rdm/smn for progression. You'll never avoid situations where your group is thinking "Maybe we wouldn't have wiped here if we had a rdm/smn".
If it's about stereotypes, if anything we should be asking why people are so fixated on 2 melee 1 range 1 caster, when you can do 1 melee 1 range 1 caster and still bring a black mage in the flex spot. Addle is very strong, nothing has changed about black mage that made it so strong in eden 1-4. The 1/1/1 party buff setup in Shadowbringers is explicitly designed to allow for compositions like this. While the casters are squabbling, the melees are laughing all the way to the bank. In many ways, it's almost more about how people view blm vs melee, and involving summoner in the dispute is kinda like involving an unrelated party. They are not mutually exclusive picks. You could delete summoner now and people will still choose red mage instead. As long as you don't have a raise, you are competing with the melees/ranged and not the other casters for a spot.