Well, a 2600 or a Putney are (semi-)modular in nature
The VCS3 or Synthi are fullly modular in nature, they don't make any sounds unless you make connections with the pins on the matrixboard.
They are not internally pre-wired and ready to be played (unlike a 2600 or a Mini Moog), that's true, but "modular" in a sense of "give me three of these modules and four of those" they are not. They are fairly limited in terms of options and you're stuck with what you've got (they don't even have a proper envelope generator, for a start).
I do love my educational toys but I don't refer to them as "my modular rig". That would be a bit pathetic.