Switch rods are simply shorter spey or double handed rods.... 9.5' to 12' in length. They've been around for over a hundred years...yet the term is a modern term....coined in the US, by RB Meiser who refined them and opened their potential with modern materials 30 years ago.
"Bob Meiser is the American author of the switch rod. The term “switch” got that moniker because a day of casting multiple types of fly lines to ascertain the best performing combination for that “new” short Spey rod resulted in a comment about so damn much “switching” and voilà, “switch.”
The first switch rods were nine foot, nine inches and made by Meiser for angling friends who were sick and tired of physical demands created by double hauling in preparation for each single-handed cast. That was in the mid-1970s.
The first switch rod ever sold as a company product was by R. B. Meiser Fly Rods. That was in the mid-1980s."
Highlander Switch Rods - R.B. Meiser Fly Rods
Yes you can switch back and forth with single and double hand casting and switch from high sticking nymphs or indy fishing or swinging streamers with a switch rod where you won't with a longer spey rod...but that is not where the term is derived from.
In the end it is a wonderful tool that has opened my eyes to a completely new way of fishing and for it I am grateful. I have become a much better angler and caster because it has made things easier.
Whether this praise be to Mr Meiser or some nameless gentleman from the UK that first made a shorter bamboo double handed rod 100+ years ago...... is really irrelevant. I'll give it to both.