Should such be used?

YES, NO, MAYBE---depending on the exact type of fittings.  For example: Yes on nipples and No on flair fittings.  (I just hooked up a propane kitchen range in our house, some fittings required it; some it was forbidden on.)

For the pipe thread non flare type you want thread tape rated for gas.  Mine is yellow.  Do not use standard thread tape

The different colors typically designate the thickness of the tape. When we do natural gas lines we use tape then dope. I use blue monster tape on all pipe thread joints. 
 

Now let’s start the debate between tape lubricating or sealing. 

It does both, but as far as I know the colour indicate the density.

There is white that is single or double density, yellow is double density. I believe there is pink that is triple density and green that is oil free to use on oxygen lines. 

I, however, have a roll of pink 'teflon' sealant and it does not feel triple at all