I'm not sure if you or Addie are talking the truth or back-pedaling.
When we make a sign, banner, letter a truck or whatever.... unless the customer tells us this is for a 3 or 4 week promotion or the truck is being traded in, in 6 months or a year, we will letter the project doing our best. However, we can and sometimes do ask the customer if they want to go with a lesser grade vinyl or substrate, but make sure they know, we're not recommending it for their own good. This is a form of making the buyer beware, so they can make the cheap call on their own. It's also a way of tier pricing. BUT, we let them make the educated decision, we don't cut corners and think to ourselves, whew-wee, we pulled it off.
It's kinda like buying a ladder. It's tested and trued and will hold about 500lbs to 550lbs. but they rate it for 255lbs. to be safe. Well, when we do an outdoor banner, we try to make it to the specs we feel the customer needs. However, often times it will take more abuse than intended or serve their needs longer than expected, so we make these things to last. That's just something that's been instilled into me from a boy on up in all facets of my life. I do my very best, then I don't have to look back over my shoulder. I do the work to the best of my ability, then I worry about the minor things.
One thing I despise is 'Built-in-Obsolescence'. It doesn't sound like that's what Addie was originally talking about, however, what he quoted and wished he could say like you.... is not what he meant either. It was quite clear he was saying the OP here should have up-sold the project without any regards for this just being about banners lasting a long time if made correctly. He insinuated the customer was cheap. Well, in most cases, a banner is the cheap route to go, but not always. You need to design and make your signs based upon your customer's needs and wants, but with your expertise involved to give them a product worth their while.
As for you, Auto, whether a banner goes on a wall, strung across a highway or hung between two uprights, choosing the right products and properly lettering them should result in an outdoor banner easily lasting 3 years, with more than likely another year or two of life in it, if maintained. Otherwise, micro-engineering something like this will probalby just backfire for you.