> looking at the companies who buy Google AdWords on their own brand - if someone's searching for your brand on Google your website will already be the top result - a click on the ad is not a true "conversion" in this case and is just wasted money

Could be a true conversion given that all competitors are paying adwords on your brand name search also. If you don't have them you will probably appear after a long list of competitors with really personalized clickbait titles prompting your customers to compare you with them