Re: Can a grownup, please...?
Two words: legacy systems.
All the fun stuff in database development was done back in the 1980s, when "hacking" was a sport indulged for fun and kudos, not a major criminal business, and neither bandwidth nor processor power was sufficient to support dictionary attacks. The databases and textbooks we use today are linearly descended from those developed back then. It's amazing how much hasn't changed.
It's hard to change this stuff, because basically everyone is accustomed to the present regime and has an inbuilt prejudice against radical change.
There's also a whiff of faddishness about the advice in this area. For years it was "lower/uppercase plus numerals", then "special characters" were added to the recommendation, and now there's bitter controversy (see, e.g., TFA as opposed to your own comment) as to whether "CorrectHorseBatteryStaple" is better or worse than "5CWr`R?EV8]K". I can't blame sysadmins for being leery of any single piece of advice, unless and until it gets endorsed or forced upon them by a higher authority.