How is installing an executable on my machine and then entering my financial info any less sketchy than entering my data into a website? The average user would still have to take it on faith that the data isn't going anywhere, and as an industry we have spent the last 20 years telling people not to download unknown software onto their systems. I think it would be a complete own-goal for the builder of this to switch to that model.
But the default expectations are very different. The default expectation for a web hosted application is that all your private stuff is stored in a database with dubious security, and if your data is stolen as a result the only consequences are a 'whoops, my bad' (at most!) from the company.
