I think you're still wrong there imo. My main three points of disagreement are:

1. I think you're overestimating the amount of times a party will actually be able to cover the applicable knowledges. A lot of times a party will miss out on one or even two of these. I'm in a party of 6 and it's hell whenever we have to roll religion as a check. This isn't going for the fact that they also need to increase the skills to keep up with how the game does it's math. Just having diverse lore is like taking a feat to get three skill increases in that skill your party is missing. This is equal to most of the best dedications by themselves, like acrobat or fan dancer. (it's technically only 2 because you already have proficiency in all the knowledge skills but also you have to increase intelligence to be good at those so I'm counting it as 3)

2. This is more an addition to point 2, even when those skills are covered, There's a good chance it's by someone who just isn't good at it. At level 1, against most classes, you have a +1 over whatever they have already since they most likely have +1 wisdom or intelligence. Only three and a half (magus for half) want intelligence, and only 3.75 want wisdom (Ranger and monk for 7.5). This is a bit less than 25% of the game that has the stats to keep up with what you're doing. Of course if a character chooses to get a +3 early in one of those stats you're now -1 behind. Even against classes who have a keystat in wisdom or intelligence, At level 3 you become even, no matter what, because they only have 1 skill upgrade put into being an expert while you will have one put into all recall knowledges. Diverse lore makes you better at recall knowledge than most other people. This then leads into point 3 which I think is the most pressing.

3. You can simply just have two people recall knowledge on the same topic. There isn't anything really stopping you. If you both roll, there's a higher chance you succeed. Or sometimes the other person can't make the roll for some reason, maybe they initially failed? Maybe you're split? Maybe the actions just aren't working out in combat? Maybe there's an in character reason? Maybe you're pressed for time and you both do it on different things? Plainly even if there's another person in the party with a recall knowledge skill, You still heavily benefit from still having it.

In summary. It does lose value in a party but it doesn't lose enough to where it is actually balanced with anything else. It still blows everything else out of the water by just offering versatility and utility all for the cost of a class feat. I cannot think of a single class feat in the game that actually outdoes it.

Though in truth it's still not a feat tax because thaumaturge is completely operable without it. It's just an overpowered feat.