[ssivark]

Could it be that such increasing specialization (sales, accounting, coder, glue…) is driven in part by decreasing attention spans and ability to focus? Maybe nobody is able to exert significant deliberate cognitive processing on anything beyond a narrow slice that they are already comfortable with.

[jasdi]

It's natural. Rate of change is increasing in all fields. So when teams can't keep up, another team is setup to handle whatever is new and then automatically you get divergence in expertise, between the two groups over time. If you specialize in selling on amazon you learn totally different things, than selling in a store. If you specialize in mobile app development, a gap grows with teams who work on web or desktop. Info Asymmetry and Knowledge Gaps between specialists keeps growing with time. So the glue people naturally emerge.