I've got 3 of the 4 front air struts on my 2003 and 2012, all with lifetime warranties, but have never had to use them because they're all working fine.
Keep in mind that the original LR air struts apparently fail (un)reasonably often, as do any of the replacements other than Arnott - or else this wouldn't be an issue and wouldn't be a major topic of discussion for the L322.
As far as Arnott's lifetime warranty - it is a limited warranty in that it is not transferable from the original owner.
That's the only caveat to it that I've heard of, with complaints from subsequent owners trashing Arnott because they couldn't get replacements because they're not the original buyer and couldn't provide proof of purchase.
But come to think of it, if they didn't do this, there would be more risk of getting non-Arnott parts back from people trying to work/take advantage of that system.
Considering that, it sounds like a reasonable constraint to me!
I agree with "But there is some truth to part warranty being worthless. When a certain brand of part fails prematurely and you have to re-do a repair, do you really want the part replaced with the same or go with something that lasted longer? " in a certain context.
It certainly applied to many store brand parts, moreso long ago than the last 10 or 20 years, since production control & quality of cheaper parts has improved dramatically.
In the mid '80's I used to go through Discount Auto Parts own label of starters on my '75 Monte Carlo annually. Lifetime warranty, but they counted on the customer to get tired of replacing the same one that kept failing.
But then again I think the main culprit was the sensitivity of properly shimming the starter when installing.
Unfortunately I wasn't familiar with that finer detail on starter installation until after I sold my '75 Monte Carlo.