But only if you put the tape over the edge. I usually leave the first 2 threads uncovered, why would it fall into the stream if you don’t cover the tip of the thread with it?
The most installed/removed NPT thread will leak the most thus have the most tape added and the scraping of installation/removal will guarantee teflon contamination of the system eventually.
You are also correct in that something installed one time for the lifetime of the system, especially with some care and attention to cleanliness, is almost certainly OK.
Its not that the Teflon reacts with hyd oil, its that the inevitably little tiny bits of stuff physically jam/ruin seals and clog nozzles.