Uh, I mean, that's not true at all. There was ~18 months between the PS1 games, another ~18 months between GT2 and GT3, and roughly 42 months between GT3 and GT4. The only gaps involving four years (roughly) would be GT4–GT5 and GT6–GTS.
I believe the point being made here is that grouping FM7's version of lootboxes in with something like, say, the early-day version of lootboxes in Star Wars Battlefront II is (possibly intentionally) misleading.
FM7's boxes
never cost real money. FM7's boxes
never featured content you couldn't unlock traditionally elsewhere*. The only thing lootboxes really offered were self-applied nerfs to gain extra credits.
* - IIRC, badges and outfits were indeed pretty much box-only, if you care about that sort of thing.
If anything, this whole discussion shows that there are shades of gray here. There are the Wheelspins in FH4, which functionally aren't much different to boxes. Going in a different direction, there's GT Sport's Daily Marathon. You're not using credits to buy it, but it's still an in-game mechanic urging you into putting time in for the chance at a prize.