How is it a marketing trick? Can you please explain.
Because anyone who understands how bitcoin works, and understands what transaction batching is, will be thoroughly underwhelmed by this. Individual users like myself have been using transaction batching for literally years. If we can do it, then there is absolutely zero reason that arguably the largest and most valuable bitcoin related company in the world couldn't also do it years ago. In reality, the fact that it took them
this long to finally implement it should really be a source of embarrassment for them, not something to announce to the world as if you are making some massive progressive strides forward.
They have announced it with great fanfare, and a bunch of newbies who don't understand any better will think "Oooohhh, they are saving me some fees, isn't that amazing! How great are Coinbase!", whilst anyone who understands what is going on will just roll their eyes.
Coinbase has always been an exchange for users to easily interact with cryptocurrency. So I can see why they would have taken longer on this, it will slow the process down a little bit doing this as they have said in their blog post. So since they are trying to make quick and seamless transactions they needed to make sure they could implement it fully without any problems.
We are talking about a fully regulated exchange. Coinbase isn't going to do things like Bitmex.