Little things: no. Developers should be free to make day-to-day technical decisions without some nosey PM micro-managing and distracting them.

But PMs should definitely be involved in big architectural decisions, like:

• Should we switch from Oracle to Postgres for all our customer data?
• Should we move from AWS to Heroku?
• Should we kick off a year-long test automation push?
• How are we going to scale to 10x current load?
• How should we support our first non-English customers?
• How much effort should we put into improving performance?

Note that “involved” doesn’t mean that PM should drive or own these decisions. Engineers are the primary owners of technical decisions. But PMs should be involved, where I think “involved” should mean at least:

• PM understands the reason for doing the work, and can explain it to others in the company who question why it’s needed.
• PM understands the costs and benefits of the work, and the tradeoffs (e.g. usually slower delivery of short-term features in exchange for a better long-term story).
• PM understands the risks and fallback plan in case the work doesn’t go as expected
• If there are several options being considered, PM should be exposed to those options and should inject a customer/business perspective as options are being weighed against each other.
• Engineers should convince PM that the work is justified. If you can’t convince the PM you work with every day, then do you think you’ll convince your CEO or head of Marketing who won’t have the patience or interest to learn the details? Convincing PM is a necessary dry run for the really skeptical folks.
• Engineers should be willing to entertain legit concerns, especially re: customer experience or delays to the roadmap, that PMs bring up. Remember that code is there to serve the business, not the other way around. PM input may be intrusive, but not nearly as intrusive as having the company go bankrupt before the big infrastructure project is done!

In reality, PMs generally serve in an advisory role for these kinds of big architectural decisions. They can be a separate and useful set of eyes to make sure that a big investment is made with buy-off from the business and awareness of what can go wrong. Rarely, PMs will push back on infrastructure investment. You can probably override a “PM Veto” but it’s much better to bring your PMs along with the process. It will pay off later… especially if the work goes south.