How do you balance messaging to developers when (in b2b) they are usually not the buyers?

You have to message and target both, with different messages/tactics. 

Example:

Let’s say the platform team evaluate the product themselves. If the developers don’t see enough value in the product then they won’t use it, and the product will fail. My guidance is to understand the end user (developer) and the buyer needs and arm them with both. Target the developer as your champion if they are the end user by making a product that solves their use cases, and stay out of the way. Don't bombard them with sales, gradually let them find product value and then enable them with content for the buyer to convince the sale.

While developers may not be the buyers in B2B, they are most certainly influencing the purchase decisions. Developers also influence purchase decisions in their personal and professional networks outside their organization. Your executive and buyer audience will care more about ROI, scalability, no. of integrations, and security posture. Whereas the developer and end users will care more about technical details like performance, feasibility of implementation and real use case examples with demos and sandboxes. These audience segments are not always mutually exclusive, and developers today could be buyers and executives tomorrow. Hence you are right in needing to balance the messaging. Three ways that have worked for us are:

1. Create separate messaging and assets highlighting product benefits for both technical and non-technical audiences. Tie both to overall business outcomes like saving cost/time/resources, improving efficiency, or speeding up innovation that everyone will relate to. 

2. Map your buyer/customer journey content to assess whether you have enough coverage across all stages of the lifecycle. A lack of good onboarding and adoption-focused content, such as technical webinars and use case guidance, can create customer retention problems.

3. Test your messaging and personas regularly, yearly if possible, to ensure your understanding of the customer pain points is current, and your messaging is still relevant to both buyers and developers.