It would be cool, but transactions are two way. Its technologically not gonna be too difficult to create a way to buy with stocks (cashapp could probably add the feature tommorow if they wanted) but its also about the other party's willingness to recieve payment in stocks. If the price is expected to go down, they're not going to want to receive it (inflation). If the price is going to go up, you're not going to want to part with it (deflation). But what if there was some sort of asset that had an agency backing it to try and control inflation and deflation to ensure that the value of the asset is stable over time, so it can be used as a currency? Wait a sec...