issue only when matched up against the design and hardness of the rod and reel component it comes in contact with. And we have some seriously hard materials in the list above.
The site of maximum line abrasion on the rod is the stripping guide, then, to a much lesser extent the tiptop, and then all the guides in between. This is because, for serious tension of line, the ANGLE of fly line movement can and often is greatest at the stripping guide. The tiptop experiences almost continuously a great angle/low tension or shallow angle/great tension scenario. The rod body guides never experience great angles but significant tension at relatively shallow angles.
There are many common, minute to minute fishing ,scenarios in which there is angled line movement over the stripping guide, but the one maneuver with the most abrasive potential, both high tension and high angle, is the single haul. We perform a single haul (aka Forward, more accurately FIRST, in front…lifting… haul) as part of almost every cast at least once, and often repeatedly with each false cast until the line is delivered out front again.
The angle between the hauling hand and the stripping guide during a haul can exceed 90 degrees, and with a LOT of tension! There are those who argue that the fly line should never be stripped off a reel in a way to angle against the line guard….due to damage caused to the line…but they universally ignore that they are doing exactly the same thing multiple times in EACH CAST at the stripping guide! One might strip out line, say 20 times a day. One executes a forward haul HOW many times in a day…..500, 1000?
Enter first the agate stripping guide, then eventually the modern ceramic insert. Problem solved.
The assault on guides from abrasion with the development of the weight forward line, replacing double taper lines, and the double haul and shoot….longer casts and more line movement, eventually caused a metal replacement of ALL guides. The earliest common guide metal was “German” or Nickel silver, the same metal used for all the rod components .The first replacement material for the tiptop and snake guides was stainless steel. For the stripping guide, without an agate or ceramic insert, the abrasion is so concentrated that the line would eventually cut through stainless steel altogether. We know this because stainless steel, at least in the alloys initially placed of rods, was found to seriously score at the tiptop and to a lesser extent in the snake guides, just not as quickly as nickel silver. There were a few instances of an agate insert tiptop, but the bulk and weight on the tip interfered with rod action. For a few years until a harder material was found it was common to check and occasionally replace the tiptop and less commonly all the snake guides as well.
The third generation guides, our current best solution, are a family of hi tech alloys starting with chrome plating, then Titanium and Chromium carbides, and others, most commonly as a superficial coating over base stainless steel. The result is light, bright, corrosion resistant, reasonably inexpensive, and very abrasion resistant.