"Wonder why so many go to the expense of buying a set of graduated packing strips for home use?"
Convenience is why. An example? Yesterday, I needed to find the gap between the rear of my dig read head and the base of my milling machine. A .124" slip quickly gave me the answer à la feeler gauge. A bottle gauge and mike would not have been a lot of use for that nor for that matter would a pair of inside calipers as there was not enough room to take a reading.
Owning a set of slips is not owning a tool but a whole box of tools. They are truly universal in their use.
Home use? Mine are only ever used in the workshop!
Until you have used a set you'll never know what you are missing
Rik