I sure hope you're right. It wasn't drilled into me when I was in engineering school (mid-2000s), but I will heartily confirm that operators are a fantastic resource. Interviewing operators is definitely not optional if you want to succeed. Engineers who just leap in often look foolish and face a lot of resistance getting upgrades implemented (well, ideally at least).
That said, operators tend to be masters of their section, but do not often have a comprehensive high-level view (excepting relief operators, who need to have a good idea of the whole process to cover multiple positions). As a result, I treat their input as a deposition or raw data/evidence: pure, unfiltered signal. Some interpretation is likely needed to make it fit into the overall whole of the process, but it's miles away better than guessing or just trusting assumptions!
Process engineering is a comprehensive and collaborative field. Leave operators out, and you're just not looking at the process. People matter. A lot.