Why not just send paid traffic to my website?
Because your website serves every visitor and therefore converts none of them optimally. A landing page that repeats the ad's specific promise, removes navigation escape routes, and asks for exactly one action consistently converts better, and on Google Ads the tighter relevance also feeds Quality Score, which lowers your cost per click. The platforms here exist to make those dedicated pages cheap to produce and test.
Should I pick a conversion platform or a site builder?
Decide by your binding constraint. If iteration and testing velocity on campaigns is the bottleneck, the conversion specialists, Unbounce and Instapage, earn their fees with built-in experimentation and ad mapping. If brand-grade design and owning a full marketing site matter more, Webflow or Framer give you one system for everything and you bolt testing on. Teams commonly run both: site builder for the site, conversion platform for campaigns.
How many landing page variants should I test?
Fewer, more different ones. Two or three variants with genuinely distinct angles, different offers, headlines, or social proof structures, beat ten button-color variations, especially at the traffic volumes most campaigns actually have. Let a test reach statistical confidence before declaring winners, and on heterogeneous traffic consider Unbounce's Smart Traffic, which sidesteps the single-winner assumption entirely.