I use Tailwind for a SaaS app because of TailwindUI and I'm pretty happy with it. I also used the Marketing page examples to put together a website[1] pretty quickly.
When the app UI gets more complicated the need for design skills definitely creeps in. But, taking a step back, using a wireframing tool like Balsamiq, and having another look through the component catalog has gotten me pretty far. I'm happy with our ability to ship quickly.
Just an FYI, the logo on the site you posted gets deformed on mobile when there’s not enough space for it and the buttons on the right to live all on the same line.
[1]: https://truerev.com