It's not deep until someone shows up to talk about his diesel Grand Cherokee or Chevy Cruze.
This is good advice for people who intended to use the full capabilities of their HD truck. At least in the Ford and GM lineups, there are typically few differences between a 3/4-ton and a 1-ton SRW other than badges, spring packages, and the all-important sticker on the doorjamb. (Ford has introduced some minor differences over years, such as rear axle spec.) Practically speaking, the difference usually comes down to a bit lower ride height and a bit softer ride in the 3/4-ton.
I believe the current Ram has multi-link coil rear suspension on the 2500 and leaf on the 3500 SRW, which is obviously a more substantial difference.
The single biggest reason that a 3/4-ton exists for private owners is perception; many buyers think that a 1-ton SRW would be "too much truck". For commercial users, there are often advantages to keeping the GVWR at 10k or less, as greater than that will require a CDL in some states (regardless of actual payload) and/or cost more for registration fees.
Making matters even more confusing are packages like the "High Capacity Tow Package" that Ford now offers on the F-250, which effectively is a F-350 SRW in terms of GCWR but with a lower GVWR. Since this package isn't available with the "wimpy" 10k GVWR spring option (and since the 30k GCWR puts it into CDL territory for commercial use in most states), it serves no "real" purpose other than marketing (and for the marketing guys, that's a very real purpose). The lower GVWR might very well come back to bite someone when it's time to use the full GCWR, since some of that ~22k trailer needs to go on the 5th wheel pin, but hey, at least they don't have to take admit they bought a 1-ton truck, eh?
If it were up to me, there would simply be SRW and DRW HD trucks, and we'd get rid of this nonsense. I look forward to getting lit up by the cranky bastards who are still living in the days when Ford used the TTB front axle on F-250s and a solid front axle only on the F-350.