There seem to be relatively few themes out there, but it seems the intent of Tailwind is that you are building a custom design. There is no reason these themes couldn't exist, but you'd also want custom some components to completely break away from the behavior of the ones supplied.
Your question is intriguing to me because I come from web development long before the Bootstrap was available. Teams I worked on would frequently take custom designs and turn them into clickable HTML templates with all UI components before spending a lot of time with the site itself. Bootstrap took this a lot further, but also enables the early parts of design to be skipped. You then have your issue with the site looking like a Bootstrap site.
My personal opinion is that Tailwind along with this new offering enables a better way out of that situation. Bootstrap is still known to more people and has less of a learning curve which are important points for some.
Your question is intriguing to me because I come from web development long before the Bootstrap was available. Teams I worked on would frequently take custom designs and turn them into clickable HTML templates with all UI components before spending a lot of time with the site itself. Bootstrap took this a lot further, but also enables the early parts of design to be skipped. You then have your issue with the site looking like a Bootstrap site.
My personal opinion is that Tailwind along with this new offering enables a better way out of that situation. Bootstrap is still known to more people and has less of a learning curve which are important points for some.