I think, this a very common opinion. But I am not sure whether I agree.
Not only when I compare different schools like shodokan , aikikai, aiki no michi, ki aikido. But even when I train in different dojo of the aikikai here in Germany it seems to me that the different branches of the "only one aikido" are develloping in different directions. That the different styles or schools or aikido are drifting apart.
Yeah, that may be the case indeed, but that doesn't mean that is correct. There is only one aikido and that is o'sensei's aikido, based on the basic principles that he taught. Everybody who say that they are teaching another style, they don't know what they're saying! And then of course, they engage in endless discussions wondering about the magical secret of o'sensei's skills...Beats me!