Disagreeing with you doesn't mean I'm combative. (Not that I care)
> typography or design as disciplines that warrant serious thought.
We are talking about fonts here, more specifically fonts used in software, more specifically the quality of free fonts used in software. Not 'design' as a whole which is much more than that.
> System fonts are the absolute bottom of the barrel.
If you say so.
> You're associating your product with the ocean of amateur work on the internet, giving the impression you copy pasted a template.
Reusing a font means you're copy-pasting your article/app/etc from a template? Erm ok.
> There are some high quality free fonts typically backed by massive organizations with actual typographic expertise.
'Some'? Like 1000? 10000? How many fonts does one application need? 'typically'? How 'typically'? And I'm not being pedantic - your statements are pretty meaningless without actual numbers.
> Professional fonts are well designed at all weights, they're carefully spaced, they include much larger character sets to support more languages, contain features like lining and non-lining figures, variable font weights, small caps... are those all slight differences?
What is a 'Professional font'? lmao
Plenty of free fonts have all of the features you've listed, and plenty of non-free fonts don't.
> There’s a reason so many articles exist with titles like “Google Fonts That Don’t Suck”. Most of them do.
Again 'so many' and 'most'... you should provide specific (at least approximate) numbers, otherwise this says nothing about how many good free fonts are actually out there.
> Arguing that all design is BS is just lazy
Well I didn't say that, pretending that I did is pretty lazy tho.
> I highly recommend practicaltypography.com, a free web book that discusses all of this and more, including why system fonts are bad and why a professional typeface is worth paying for.
Oh geez! A FREE book which tells you why you should pay for 'professional' fonts while at the same time selling them to you with affiliate links! Thank you sir!
Also: they're pretty clearly wrong, so you shouldn't need any of this to refute them.