I'm not sure why every "Show HN" post attracts somebody that points out that what OP has created isn't novel. It's a big world and novelty isn't half as important as quality of execution and UX.
The purpose of these posts isn't to lay focus on what's already out there, but to focus on what OP has created, usually for the primary purpose of critical feedback so they can improve themselves and their product.
That would be perfectly valid criticism. If they'd said "there's x and y competitors and they do [...] really well - might be something you'd want to look at because these are very heavily used features", that'd be really constructive feedback. But all noodly said was "theres already one" and solicited contributors.
I prefer the usability of the OPs much better. The use of dollar signs might be a little clunkier than the begin/end tags when you want to use a dollar sign. But all in all I think the presentation is better and a bit more welcoming.
I disagree about dollar sign. This is how embedding mathematical notation in LaTeX always worked, and I never had, nor heard of anyone having problems with that in practice.
