At that point, don't respond then :/

here's how I would've responded:

"Hey my project targets the niche similar to notion and others who are also web based for the most part and subscription model, reading your comments, you might be better of using non-web products and some of the suggestions in that include Qownnotes and zim. Here is a video in detail which talks about Simple, Non-Commercial, Open Source Notes for example which might help you find a solution for your needs: https://www.youtube.com/watch?v=XRpHIa-2XCE"

(Not saying that you needed to refer them to alternatives but as I knew of this video, if I were you, it might've made sense)

Another comment which doesn't talk about any other software but might've worked as well if you wished to respond:

"Hey, at some point, I do understand your take of everything turning into electron and browser-ified and software is taking 1 gigabyte of ram etc. and I understand this sentiment as well but I feel like that there is still an opportunity to make browser based subscription models towards the people who still wish for something convenient within their browser and for example, these can work absolutely great for students with their chromebooks which can have browser apps with genuine ease and targeting a large group of people to gain feedback from to hopefully improve my product even further in the future."

> Web-based and subscription payments describes the majority of software out there today

Yes and people are fed up of that too. I am sure that the alchemist isn't saying no to your product but saying yes to, for example notion. They are saying no to both and they are making their stance clear (as to why) and you are bound to have some people who are on the fence about the same thing (especially if you are launching within something like hackernews)

Edit: These are all thoughts that I can think of not even having launched anything from this product but I have sure tried my bunch of editors. I am definitely certain within your ability to write such messages as well and if you aren't, then that's completely fine too and I recommend in that case to not reply back for example.