That doesn't sound like a solution. Some people might have really good financial tweets but your solution would be to unfollow them for their irrelevant ones.
Yeah, some people post good stuff but their signal to noise ratio is just too low. Not much choice but to unfollow them.
Or Twitter could let accounts create categories for their tweets so that you could opt-in or opt-out to them when you follow people. I may be into finance but I want to be able to post other things too, as I'm human. Trying to juggle multiple accounts is frustrating and time-consuming, and often thwarted by randomized phone number verification requirements on new accounts.
That's solved by being stingy with your follows and not being afraid to unfollow people. From my experience I have zero issues keeping my stream focused on finance (though i do follow one or two comedy accounts that post every once in a while)