Clarification on manual hubs

Hi all 
please can i get some clarification on manual hubs because after learning about them today i have found myself down a rabbit hole with the article on the wiki and youtube videos and still confused. 
this morning before uni i did my 2 inch suspension lift. I noticed when doing the fronts that the two metal pipes leading to two braided lines attached to the hubs were practically none existent. They have completed rotten away in places. Now i havent had to use 4 wheel drive yet so not sure if a light would come in or not but whilst researching what these pipes where that ran along the to of the front diff i found put that they are vacuum for the hub 4 wheel drive system. 
Knowing that i will have to do something about it before taking the jimny out in the mud i came across all the info on manual hubs. 

so am i right in thinking that basically on the transfer leaver (2003 car so not a switch). With them in the unlocked position both 2WD-H and 4WD-H are 2WD-H and 4WD-L becomes 2WD-L and in the locked position 2WD-H is 2WD-H, 4WD-H is 4WD-H and 4WD-L is 4WD-L 

does that make sense and have i got it right? 
I feel stupid for asking but my brain is working only in one way about this

TIA

With the hubs unlocked, putting the transfer case into 4wd will only make the front prop spin, it won't drive the front wheels. Low or High makes no odds for this.

To engage the front wheels, you'll need to lock the hubs as well.

TBH, unless you have a very specific use case, I don't see why anyone would want manual hubs. Very 1950's.... tech.

There really are only minimal gains to be had by unlocking them. And who buys an off road Jimny for mpg reasons?

Plus, I don't understand why you'd want a 4wd system that requires you to do something in the cabin, then park up and get out and mess about in the mud on both sides of the vehicle, just to use 4 wheel drive.

I haven't checked prices, but surely replacing/fixing some vacuum lines must be way cheaper and a lot less labour than going for manual hubs?

Thanks for defending the vacuum hubs!
My SJ got straight solid hubs locked. Havent bothered to put manual hubs there even though there is a few sets in stock.

I like my vacuum hubs, fixed them too.
I am forming the vacuum-party!
Open for all vacuum users anyone with hubs can join, but no pressure!

The Vacuum Party.
- it sucks