Sounds like a crazy conspiracy theory 😉 I mean, maybe there was a plan to use that for circumventing blockade of ninjamine account(s), however the feature is one of the early features of legacy chain. Here is the initial commit that introduces it, and here the one that renames it to current name. Both from June 2016.

Also I'm not sure it was actually a soft fork that was used to block transactions during that time (it was marked as minor version though) - calling @gtg who might actually know the details. When you have nontrivial stake, soft fork is easy to circumvent - a single backup witness is enough to push your transaction through. Also as far as I know the goal was also different - to vote in enough top witnesses controlled by JS, so he could single-handedly dictate the fate of the network. Selling the ninjamined stake would be contrary to that.

In fact the routes can be split up in as many different ways as the user wants.

...as long as it is no more than 10 ways 😀 Allowing unlimited routes would be an attack vector.