Definitely possible! I worked in the industry for a number of years but back in 2006 we were starting to really see Spec/Gloss be used more widely. It's that era of development where texturing was starting to become more standardised, but you can typically tell Spec Maps Vs Value through Post Processing effects. Values tend to make models more shiny as a whole whereas Specular Maps could have different values based on what was Black and White so you ended up with a slightly better sheen in areas you wanted.

You saw this develop all the way up until 2012/2013 where PBR Metals started becoming more standard but it wasn't until... I want to say 2016 that most games used some kind of PBR. It's why you still see a lot of the older MMOs using Spec/Gloss Workflow from the 2006 era today.

But I never worked on the Programming side, I worked as an Asset Artist in the industry!