"Nobody gave up anything. The founders would have received a portion of the stake in the very beginning.

Founders:  David Lazovsky, Michelle Tomasko and Preet Virk. 

This is the same idea as POET having a stake in SPX by providing technology skills while the other side provides capital and facilities."

you're right it's the same thing, if we neglect time and many other things.  The founders would have had 100% in the beginning, or 2015.  They did not create a JV in 2015 and then announce their partners after the VC rounds several years later.  Many VCs do like to have their hands in the execution but not to the level of a JV.