Ford should have introduced a new platform when they re-introduced the Ranger back in the USDM. As usual, bean counters get in the way on innovation. If reviews say anything, is that Toyota has a loyal following despite the Tacoma coming up short in some areas. They are overpriced anyway and fanbois keep the used prices up.
As for the GM, I don't think it's the lack of sales for the diesels, they are just hard to come by and some people can't wait, so they move on. The interior is still horrible and the plastics are shit. They are only good for fleet work trucks on construction sites, city/county government utility yards and refineries. GM is now back in the fleet sales game since 2018 after having to leave it when it went through bankruptcy in 2008. Fleet sales for many GM dealers can account for as much as 40% of their sales a year. Anyway......
If one honestly looks at how people use their mid-size trucks, a vast majority of people can get away with the Ridgeline or something similar. After that, it's minor excuses and ego come into play.