AI's spike effect on PMF

Brian Balfour, Founder & CEO of Reforge and former VP of Growth at HubSpot, joins Mostly Growth to explore why product-market fit is a moving target. He introduces the concept of the Product-Market Fit Treadmill, a state where rising customer expectations and competitive pressure make it harder than ever to stay ahead. Brian breaks down how AI has accelerated PMF collapse, explains the hidden costs of product adoption, and shares how Reforge shipped five AI-native products with a team of just 20 people. Packed with frameworks, strategic insight, and startup realism, this episode is essential listening for product leaders, operators, and founders navigating the next wave of GTM.

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LINKS:

Mostly Metrics: https://www.mostlymetrics.com

CJ on LinkedIn: https://www.linkedin.com/in/cj-gustafson-13140948/

Growth Unhinged: https://www.growthunhinged.com/

Kyle on LinkedIn: https://www.linkedin.com/in/kyle-poyar/

Brian Balfour: brianbalfour.com

Brian on LinkedIn: https://www.linkedin.com/in/bbalfour/

Slacker Stuff: https://www.slackerstuff.com/

Ben on LinkedIn: https://www.linkedin.com/in/slackerstuff/

https://brianbalfour.com/four-fits-growth-framework

https://x.com/amasad/status/1981201454032703662?s=46

https://getlatka.com/companies/firefliesai

https://x.com/rowancheung/status/1988218743952916537?

https://gamma.app/insights/how-we-built-a-usd100m-business-differently

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RELATED EPISODES:

When the marketing math doesn’t math | with Emily Kramer

https://youtu.be/sSuoV_YSrlw

Why Founders Are Posting Sad Dinners

https://youtu.be/Zl6NSIHF2Gk

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TIMESTAMPS:

00:00:00 Preview and Intro

00:01:51 Sponsors – Pulley, Metronome

00:04:11 Introducing Brian Balfour & Reforge background

00:07:22 Evergreen frameworks & Four Fits resurgence

00:11:01 PMF treadmill and rising expectations

00:14:26 AI shocks and PMF collapse (Chegg)

00:16:43 CRM expectations & AI-native workflows

00:20:44 R&D as ongoing cost to serve

00:22:26 Customers buying based on future product velocity

00:24:32 Communicating rapid releases & driving adoption

00:25:17 Reforge’s expanding AI product suite

00:27:52 Product delivery vs. product adoption bottlenecks

00:29:32 Platform distribution shifts introduction

00:30:51 Evaluating emerging platforms

00:32:04 The open → close platform cycle

00:33:31 Moats, escape velocity & platform dominance

00:36:32 Choosing major vs. emerging platforms

00:40:22 ChatGPT dominance in AI discovery

00:42:16 Hiring, resumes & filtering AI-generated applications

00:43:30 AI note-taking market & “Flintstoning”

00:47:03 Trying Gamma & AI-generated presentation tools

00:50:08 AI onboarding innovations (WhatsApp agent)

#MostlyGrowthPodcast #ProductMarketFit #BrianBalfour #StartupStrategy #Reforge

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