'If your app is for everyone, it's for no one'.
That is, to be really good at X, it's necessary to trade off some Y. I'm innately distrustful of software that won't tell me what that Y is. Since everyone is shouting that they are the best, I find clear disclosures of what a tool is bad at to be a really useful way of cutting through the puffery and finding out if it's right for me.
Also, provided Y isn't something that I care about, the larger it is, the better. Opinionated Software is great, but Very Opinionated Software is brilliant, if it shares your opinions.
I'm finding that this is an effective way to generate clarity at the beginning of personal projects. Instead of exhaustively defining what it is, I define what it doesn't - in fact, will never - do. I call this 'FAQ Driven Development'; there's a somewhat tongue-in-cheek example of it here: https://dosofe.netlify.com/.
Also I really like what Standard Notes has done in this space. The core app itself is not just feature-resistant, it's downright feature-hostile.