Part of the issue is that those assumptions of relatively short ranges were reached in an environment of actual fighting in jungle environments in Vietnam, and

Part of the issue is that those assumptions of relatively short ranges were reached in an environment of actual fighting in jungle environments in Vietnam, and prospective fighting in built-up or forested environments in Europe. In arid regions, battle rifles with their longer ranges and lower volume of fire are arguably a better tradeoff. See, for example, the use of early-20th-century British battle rifles by the Taliban (https://atwar.blogs.nytimes.com/2011/01/31/taliban-gun-lockers-the-rifles-of-rural-ghazni-province/ https://atwar.blogs.nytimes.com/2011/01/31/taliban-gun-locke...), resulting from terrain like the title photo at (https://atwar.blogs.nytimes.com/2010/04/19/a-firsthand-look-at-firefights-in-marja/ https://atwar.blogs.nytimes.com/2010/04/19/a-firsthand-look-...) (Their use is deterred by other factors, namely ammunition availability and concealability.)