I think it's because it's relatively straightforward to accomplish. These guys can work on creating stuff like this and put on their portfolio they created "Noun.js" and it 'looks good' to those not in the developer world and knowing a new one is out every week.
I consider them somewhat fluffy and learn just to say nice job and move on.
Digital Ocean's website is following a pretty standard design trend that has emerged over the past few years, the long scoll page with numerous horizontal sections. Lots of sites look like that these days.
There are far more differences than similarities. I would analyze them more before making an accusation (didn't sound like you were just trying to harmlessly point out the similarities).
I consider them somewhat fluffy and learn just to say nice job and move on.