Earlier quoted context omitted.
No you can't. The protocols for buying and selling or making payments haven't changed in decades. The problem is communication authority and scaling, not the data format. Blockchain enables so-called triple entry accounting. Everyone sees everything everyone else is doing (if you want them to). There is never an argument about who did something or why. Just consider the audit and servicing cost savings.
You can do all that with a centralized db and Merkel trees. The technology has been around for 40 years.
There's a lot of details that go into running something like that and none of those questions are trivial.