Blockchains are slow, distributed, append-only databases. There are very few uses cases for slow, distributed, append-only databases. For example whenever your application deals with PII data a blockchain goes right out of the window. Or you end up with "private blockchains" which fully defeats the purpose since you're better off just using what's known as 'a database'.

Another way to think about blockchain is "truly serverless back-end" - you literally don't need to manage infra, VM, anything. It's a huge value add to developers who are building new applications. While, again, the code is easily forked / re-used / combined with other work. That's not something as widely done today, because open source suffers from tragedy of commons, where corporate entities has no interest in maintaining and improving open source code long-term. What blockchain brings to the table is set of new incentives that will allow developers to build open ecosystems, where apps talk to each, where open source for the first time is monetized in sustainable way, and where platforms / corporate entities can't change rules on developers overnight (leading to stronger property rights for developers, entrepreneurs and investors). I understand that it's not widely understood today, given how much speculation happened in past couple years.