There is no welding required on these tanks.
What we're discussing is the additional strength, for bashing your tank on the rocks and such, obtained by giving the sliding inserts a quick tack weld once it's installed and positioned where you like it.
You can run the tank for decades without adding a single weld.
So, it's not at all a requirement for installation, and frankly most people never do anything like that even when their intended use for their Bronco is to be out pounding on the rocks. They may think about it, but just never get around to it.
The hardcore rock crawlers will do it, because that's what they're focused on. And the hardest core rock crawler builds likely won't be using this tank anyway, because to them every inch of ground clearance is more precious than an extra horsepower, or mile per gallon is.
We have the suggested extra measure in our instructions to add one more layer of security for those that need it. We "highly recommend" it because it's actually a great idea. As is thread locker when it comes right down to it.
Whether either become an absolute necessity or not is entirely up to the use the individual Bronco-user puts their rig to.
Paul