Zack, I now realize that someone added the filter in the stock DI location sometime in the past. So, yes it's possible. I think that rather than causing problems, the finer filtration of an external filter, may prevent fuel injector trouble. Even with the external filter DI's and my Range Rover had to have their injectors cleaned occasionally. As you say, "To each their own." Thinking back to my old Renaults, they had neither fuel filters of any kind, or exhaust valve seals. Best practice? Or cost savings?

'99 Discovery II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S