I think anyone who discredits brand as a function of growth is living in an early 2000s era of B2B marketing that doesn't exist anymore. The truth is that behind every logo we are trying to sell to as vendors, is a human (crazy, I know). These humans have a job to do, and are trying to self-actualize in their careers by solving business problems, getting recognized, promoted, etc. Your products can help them accelerate up Maslow's funnel, but products aren't the only thing.
You can measure brand in so many different ways. Content & conference marketing sourced (literally) 80%+ of ARR at Gainsight, and probably influenced all 100%. These were content programs and events that had nothing to do with our products, and everything to do with our category. At Front, we ran a PR campaign last week announcing our Series C that directly correlated to a 192% increase in web traffic (against our daily average) and more than 3x the number of trial signups. That's all real revenue, directly attributable to brand.
In terms of priority -- tough to answer as I've seen it both ways. Gainsight had a story that resonated long before we found product market fit. Front has had the opposite experience. In general, and since they are both opposite sides of the same coin, I think prioritizing both brand and product marketing early is key to winning in the marketplace.