It seems more and more "modern" cartridges are forsaking taper to increase capacity in a short action without increasing bolt face diameter and thrust. The 7.62x39 is an example of a very tapered cartridge so designed to extract reliably with steel cases, but even while cases were readily available in brass, many like the .30-03, -06, .270, .45-70, 9.3x62, .375 H&H, 30-30, 5.56x45, and .308, were designed with taper that's being omitted in "modern" designs like Creedmoor, Grendel, PPC, Bushmaster, Nosler, MARS, Valkyrie, and on and on. So what's the trade-off? Why did most of metallic cartridge history from the 19th through 20th centuries favor tapered cases and now we don't seem to need them anymore? Are these untapered cartridges going to fail to extract in extreme cold, heat, or with contamination from dirt, mud, snow, ice? Are they dependable or just geared toward sales to internet-researching ballistic table shoppers?