I guess if certain people want to use a brush as broad as the earth, we can always say that there are *no* founders of any martial arts since they all go back to before ... well, just before. Heck, why not just say the very first man or woman created all martial arts and there are no founders after that.
That's a classic Strawman argument: you set up a false scenario and then knock it down (hence the name "strawman"). Good one.
Why would one want to narrow the scope so that an intelligent conversation on the lineage of aikido as discussed by intelligent people in aikido could occur when someone from outside aikido could just toss the baby out with the bathwater and say there is no founder of aiki arts. That'd sure let the conversation progress. Oh wait, maybe not. No, that'd be just another attempt to derail the conversation ... hmmm ... I wonder if there's a repetitive history here ...
Well, if you want to posit that Takeda came up with his whole knowledge of "aiki" by himself with no influence from the outside, then your argument might have some merit. If, on the other hand, the "ju" arts (as in "aikijujitsu", GoJu, Judo, etc.) have some known common antecedents that were known in Takeda's time, then aikijujitsu becomes part of a broader historical discussion.
Italics, bold, underline as a marker to show where the ad hominem