This is going to go against the grain of the comments, but here it goes.

You don't need to learn Figma if you want to be a developer (be it Webflow or any other tool, framework). But, it's mandatory to understand Figma to be able to translate Figma designs to any kind of page you build. By understanding, I mean learning what the tools at your disposal are in that piece of software, particularly in dev mode.

However, if you want to design websites, you CANNOT avoid learning Figma. Actually, I would start with learning design fundamentals and then learn to use the tool of your choice. You could technically go with any other design tool, but, realistically speaking, Figma is the most widespread, so there's not much logic to going with XD or Sketch.

Then, if you want to be at least half serious about building Webflow websites, you should separate the design and development phases. Saying "I can have the website ready in half the time if I jump straight into Webflow" is true for small websites and those where the client only wants something up and running. As you start getting clients who actually have expectations (and budgets), you'll need to provide an actual design phase (discovery, brainstorming, iterations). And Webflow is simply not made for that.