You say all that, but here is one thing I find interesting...
I learnt to use a Jigsaw my father had owned for many-a-year in his profession as a "wood bootician" (Master carpenter). It was a 1970s Bosch PST50. I could cut a line in material as straight as a scale (Rule). At the time, I was not even 13yo.
20 years later I purchased a jigsaw for myself when I needed one and damned if I could get anywhere near a straight line, despite consistently using a jigsaw over the years for various different jobs. I tried different grip methods, tried using guides, tried various blade types, but nothing could solve the issue. Replaced that jigsaw with a modern Bosch blue "Professional" range jigsaw (gave the other jigsaw to a friend after giving it a clean and service) and, again, near straight cuts, but not straight.
Decided to acquire a PST50 for myself (long after my father had passed and his tools were sold, much to my chagrin!) and hey presto, I can cut a straight line again, just as perfectly as I always could. Can't explain it, don't even want to try to explain it. All I know is this old PST50 is the only jigsaw I can cut a straight line with. I suspect the "foot" has a lot to do with it.
This PST50 is still extremely clean for being at least 45 years old at bare inimum and still runs like new. It is a Scintilla SA Switzerland built unit. 240V, 1.5A, 350W, 3000RPM.
Even the foot is remarkably clean for the age of it and yes, I use it very regularly for a number of things, including slicing barstock of. Had to cut some 2" 6082 T6 aluminium with it and it breezed through that too where my more modern Bosch jigsaw struggled.