About a year ago, there was a bunch of hubbub on this site regarding spans and layers, mainly how managers need at least 7 directs and possibly 10 in the future.
Managers with fewer than 7 directs were going to be laid off, or, have their job title changed to reflect an IC status.
But with how many "dotted line" arrangements there are in this bank, it's a wonder that the spans and layers concept even exists.
Dotted line means you essentially have two bosses, which is more (not less) complicated for everyone involved.
Project managers (as an example) direct work to people all the time without a dotted line arrangement. The idea being that if you don't do what's being asked of you by the PM, your boss will have a talk with you.
If PMs can wrangle resources, delegate work/tasks, etc., then why can't everyone else that has dotted line reports do the same without the dotted line arrangement?
I just think the dotted line thing is weird, unnecessary, and only helps the person with the dotted line reports find their next job (now that they can say "I manage!").