Every business has a unique perspective regarding how products are developed and how PMs fit into that process. Here are the three most typical varieties along with advantages and disadvantages:
Engineering is driven by PM.
This is known as the "throw it over the wall" method, in which project managers gather needs, prepare the standard product requirements document, and then give it to engineering to spec out the technical requirements. Modern firms might carry out this procedure in a more flexible and cooperative manner, but it is still expected that PMs are the most knowledgeable about what customers need and that engineering is there to assist them.
Pro: Engineering can concentrate on programming without being distracted much; this usually works well for waterfall development shops with lengthy life cycles.
Con: Engineers fail to see the big picture and lack consumer empathy, which might result in a subpar user experience. When technical debt and "plumbing" work need to be done together, there are frequently undesirable conflicts over client requirements in importance.
Product is driven by engineering.
Engineering is typically the driving force behind businesses that produce more technically oriented goods and services (such as cloud, big data, and networking services); engineers advance the science in their field, and PMs validate solutions or build front-end access points (UIs, APIs) to take advantage of this new technology. Customers, PMs, and engineering can work together and provide input, but in these businesses, PMs often support engineering.
Pro: Cutting-edge technology can give clients access to products they didn't even realise they needed. At VMware, VMotion was a prime illustration of this. An engineer thought it would be interesting to implement it, a PM worked out how to make money off of it, and it ended up changing the company's game by a billion dollars.
Con: Before collecting consumer feedback, engineers chase after the newest, flashiest item, over-architect the solution, or perpetually iterate. The most fundamental consumer demands are sometimes disregarded when determining priorities from the PM.
PM and engineering together.
In these situations, there is a strong yin-yang relationship between PM and engineers, with shared accountability, joint discovery, and decision-making. PMs participate in sprint meetings with engineers to help unblock work or clarify requirements. Engineers also join PMs during client interviews. However, the boundaries between the two jobs are respected. Engineers have empathy for customers' demands but leave the priority to the PMs while PMs understand what is being developed but don't instruct engineers on how to write.
Pro: A more efficient prioritising approach that prioritises technical debt and plumbing projects; improved design workflows that result in a better user experience; higher-performing teams with better product velocity, quality, and, typically, happier customers.
Cons: Time to market may appear to slow; breakthrough innovations may not get approved. However, I would argue that what is released is far more matched with customer needs and has a higher chance of scaling.