I don't think it is case of spam scam.
I do think they really can have legit sign ups, but people "wanting to learn code" usually fizzle out quick. I have my experience as a dev when friends/family/colleagues ask for guidance, I provide them with links resources and some mentoring and after 2-3 days they don't follow up ever again.
But not using metric like daily active users, returning users, might indicate that they want to inflate their worth or they convinced themselves to believe in the wrong metric.