I’m going to get hate here but what the heck I have karma points to burn. What I have to say is not a critique of this particular project which seems nicely done but a general statement on open source.

I’d rather see more open source projects making something new than so much “Open Source reimplementation.” If closed proprietary companies are so worthless then why do so many open source projects copy those implementations. Did Wolfram really discover the one true way in its language syntax and presentation layer? If it did, is the idea of open source really just making it unviable for companies to invest in important things like that? To be clear these are of course rhetorical questions. The open source world could experiment (and in defense sometimes does) with truly new approaches and interfaces. I just want to see more of it.

Mathematica exists. Mathematica for free versus Mathematica for money is of course a nice trade. But even better would be to try new ways to interact with mathematics unburdened from legacy concerns.

I think the Wolfram Language got 80–90% of it right, and that's why I want to reimplement and use it in the first place. It bothers me that I have to use inferior solutions, such as those implemented in Python and Julia, just because the better solution is prohibitively expensive.

Of course, there are a few things I think we can do better than the Wolfram Language, but given all the available legacy code, there's really no point in making it slightly different and losing the ability to use that code. However, we might build an alternative syntax and frontend in the future that surfaces the capabilities of the Wolfram Language with a better UX.

Not mutually exclusive? The fact that money is being paid for some closed source product does at least prove there is an actual demand for whatever they figured out to do, and how. So either a marginal improvement, or simply open sourcing a subset of an existing product, or making something completely new, or better... all good isn't it?

Maybe reimplementing something that already exists a couple times over leads to good things as well. I can imagine some subtle insights could be gained which matter to some of the user base.

They spent a lot of effort on consistent naming. It's basically equivalent of hundred of open source math/visualization packages merged into one, and a single person has made sure for 30 years that functionality integrates in a consistent way. It's much less overhead to remember that using a large collection of OSS libraries. So the naming structure in itself is valuable

Closed source, proprietary license, starting at $195/year. Their language is a moat for customers, and this is a bridge back out. If you aren’t getting any benefit from their development direction and the compute is happening on your own hardware, what are you paying a subscription for?

I mean, you're basically asking why people don't do high-quality original work and give it away for free, as opposed to copying something that's successful and giving it away for free.

The answer in my mind is fairly obvious: it's far more difficult and risky to do high-quality original work and give it away for free. If you want to see more original innovative work in open source, the two main ways to achieve that are to either do it yourself, or to pay others to do it.