Or...You can have a couple real durabel one handers for different tasks and you don't have ot let go f that damn wire that was hel to get a hold of and will spring back while you're closing one blade and opening another...
I do tons of real work and often need to be able to open my knife one handed and close it the same way. ... and yes probably 3 out of 5 times a slip joint woudl and does work, but the other two times it sure is nice to have the extra convenience.
And sometimes a fixed blade is inconvenient... I carry and use slip joints, one handed openers and *gasp* fixed blades as convenient and suitable... The real joy of folders is that they are on you always, and you have them when you need them. I have no specific bias and I think all of them are useful intheir palce. to imply any of them are inferior is BS and "instigating".
As another poster said, just because the old tool did the job, doesn't mean the new one is less useful... Millions of screws have been driven with a plain standard screw driver, that doesn't make my cordless power driver less useful or effective. I'm sure glad I didn't have to screw the steel roofing on my house with a hand driver.

That said there are times when I woudl rather use the regular screw driver, such as mkaing sure I'm not cross threading into plastic or stripping a fine screw in a computer.
You are eintitled to your opinion but please don't suggest that what you did 40 years ago in the army has any bearing on the only "real way" to "real work"...