you are wrong. typst's lead dev has stated that an important goal is to have the CLI (which is open source) and web app behave identically, even refusing to implement such a basic feature as PDF embedding because, due to technical reasons, it is currently incompatible with this goal. [1]
typst, the project, is not by any means a "mix" of open and closed, even if typst, the company, is. indeed, the most thorough LSP implementation available (tinymist) is not only open source but a community project. for another funny example see typstify, a paid typst editor not affiliated with the company. [2]
[1]: https://github.com/typst/typst/issues/145#issuecomment-17531...
I believe their intentions are good, and keeping functionality the same for different outputs to avoid fragmentation is good too. An alternative interpretation, however, directly in line with the fear expressed by GP, is that they're already crippling the open source CLI because they can't support the feature in the closed source web app.