Based comment, updooted. Also, I'm pretty sure that if nobody ever "rolled their own crypto" we would never have new innovations in cryptography. By OPs argument everyone in the blockchain industry is in a state of error since using applied cryptography to design new protocols is certainly novel. But I would say that these protocols are what made me interested in applied cryptography in the first place. They are astonishingly clever, novel, and show how beautiful cryptography can be. If everyone was too scared to work with cryptographic constructs than none of the innovation that took place around smart contracts would be possible.

I see no problem with it if your work gets peer reviewed. The very last point they made though I kind of agree with. If you end up making a new algorithm from scratch that is dangerously novel and potential crack pot territory. I did like how they went to that trouble to make the hierarchy of what is meant by "rolling your own crypto."