Take a trip on the way-back-machine to the early 1970's when I was in college in NY State and was part of a very active outing club, focusing mainly on cave exploration. The University was generous with funding us, which we spent almost 100% on our favored underground climbing sport, mainly with both undergrad and grad student geology department student members, including a fantastic road trip to New Mexico to work with the Park Service exploring, mapping and studying features in the Carlsbad Cavern area and nearby cave environs with rope drops as much as 300 feet deep into previously unexplored pits and passages. At the time REI and EMS were in competition, but REI, as a member co-op had the edge with its annual cash points member rebate. Our club funding had to be accounted for and fully spent each year, or we would not receive the same amount (or more) in the next season. Most went to REI.
REI was also a much different beast then with their sales catalog packed with each REI board member contributing advice and stories about each of their own active wilderness adventures and how to best use available equipment. Of course, it was focused primarily on west coast adventure trips. I saved each catalog for years as useful reference materials. EMS also had their well stocked equipment catalog, but it fell far short in the free advice and local use department, but at least they were based in the East.
At the time, although you were legally supposed to pay sales tax in NY on all purchases, even when purchased from out of state, either by mail or in person, but nobody volunteered to pay sales tax on any mail order from out of state, and vendors did not then include the tax when shipped to NY. So that, along with EMS stores cropping up in NY State with unescapable sales tax on all purchases, the REI member rebate with "optional' sales tax, and its interesting advice columns, definitely gave REI the huge edge.
At some point later, some fool in EMS marketing decided to end catalog sales, and then completely stopped producing a mail order catalog as online ordering was the future coming thing of all sales. The only advantage for me was that my brother lived near the EMS flagship store in Peterborough NH where there is no state sales tax, and it still had relevant items for sale.
Then REI opened their first store in New York State, way down near the NYC area, too far for me to ever visit, but now there was no way to escape my state collecting sales tax on REI purchases. REI was forced to automatically charge sales tax on all purchases, no matter whether purchased in store, by mail order form, or online.
Then it all changed in a major way as both REI and EMS moved their sales focus from equipment produced for true outdoor adventure types, to catering to city and fashion folk who had more money to spend on trendy and colorful outdoor clothing and cheap unreliable equipment mass made in China. REI terminated its adventure story columns, and useful advice in their catalogs, and both REI and EMS eventually lost favor with their older base customers.