Online tax prep isn't a net positive at all. It's a solution to a problem that doesn't need to exist. In normal countries, the government already knows your income and other such info, and fills out your taxes for you; you just have to verify and sign, unless there's a problem.

Messaging apps are a bit similar: SMS is so horrible that proprietary apps were made as a better alternative, but it's all Balkanized and incompatible. Still, they fill a need, since communication is important and something people should do (tax prep is not: most people shouldn't be doing it at all).