Because A company always starts with values then they get greedy for more money.
Many people don't like the subscription based model but... You got two options, Don't pay it or deal with it.
I've thought about it honestly and at this point Construct 3 is $100 subscription for a year which is less than $10/month.
Other Game Engines like unreal want to take a cut out of your earnings.
Unity wants you to pay $25/month down from $35/month but still lock you into a sort of contract.
Then you got things like Google Plays developer fee and steams 30% of earnings...
Any way you look at it you're getting screwed, Might as well take the option that doesn't hurt so much.
Plus to be frank I've spent way over $100 for tools and Construct 3 is that, A tool.
Once I used it for what I need it to be, I'll move on. So that $100 a year isn't all that bad.