Fully agree at 100%, this is exactly what we did at Lago, use Material UI as a library, customised the CSS to make Lago-branding friendly. In that case we're not reinventing the wheel, we're using it and it helped us to go faster. I think it's just a matter of definition and our System is way far from ones you can see at Adobe, Shopify etc.
Goal is to go fast and having this base, this language between Front and Design is important to have sooner than later.
Goal is to go fast and having this base, this language between Front and Design is important to have sooner than later.