If this is the same software being used as other top sportsbooks , then the are proving to us they want quality products for their clients and I interpret this as a positive compliment!
Besides, when it comes to sportsbooks built from ground up..trust me it takes years for us to start enjoying their efforts unlike off the shelf products which are already polished and ready to go & just needs a bit of customizing to their liking, so for me this is a thumbs up.
i agree with what you said that it is not a bad thing to take what is already in the market and implement it on your platform... many companies also use the same method like this and there is nothing wrong with it-- in fact it is a good thing that whale.io uses what is already proven to work in the market, meaning they only need to develop a few things, like security, core development, and focus more on the more important things. and it also actually helps the users, meaning people who are already familiar with the interface like that will have no trouble using whale.io