Unity For Web Dev?

The software is supposed to enumerate Microsoft SharePoint permissions on a tree diagram on the web. Originally we were using D3 but had some spacing issues with the nodes and overlapping text. So the developer gave up and is playing around with Unity saying that he can compile it into webassembly and overall it allows for more control. I.e. custom right click menu, tooltips/interactive graph elements. Also claiming that webgl is more performant since the D3 graph we had was lagging a bit when expanding/contracting. I am not a developer but what are the pros and cons of doing it this way? It just seems uncommon and I get the feeling we are going to run into issues in the future when we want to implement more features. I know he tries to go back to unity any chance he can get, even for mobile app dev at one point. Thanks for anyone's insight!

I am giving the dev a chance to explain himself in these comments as well because despite the feedback i got from the other subs, he still is adamant about unity. He is now saying: "Out of the other WebGL solutions unity looks like the more complete tool set with a simple drag and drop + it's own simplified take on C#. In this case, the file size of the Unity build is small enough, so that's not an issue. Do you have other WebGL alternative in mind? Or maybe an alternative to WebGL that can match its performance so not SVG/Canvas. Keep in mind the graph is interactive with real time animations, dragging, additional elements etc…"