Given the US programs "sell" elite status, or at least a prime component of it via their credit card partners - eg: earning AA Loyalty Points, UA PQP, DL MQD etc via CC spend - at least up to certain limits - is the way these frequent buyer programs are going. I don't personally think it's right, but I am old school who put the "Flyer" into Frequent Flyer I guess. I actually think QF's "solution" to this, being Points Club isn't a bad way to go to reward the high spenders engaged in the ecosystem.
I also recall QF dabbling with the SC earn on the ground - eg the ANZ Black cards with 75 SC's and the like, green tier etc. Those are modest amounts so don't really impact on the higher status levels though.
I agree that I don't think QF would do this, but if they did, I should hope that there were limits (as the other program examples in the article have too) so that you basically couldn't buy right to Platinum, or daresay P1 (also recall the idea mooted last year about $1m spend or 1m points earn getting P1 - which thankfully seems to have gone nowhere - whichever that option was discussed in QF focus groups).
As noted above, having status is only really helpful for those flying (except in programs which provide extra on ground perks, like linked status in hotel brands), so if one did buy up to say Platinum, but only actually flew infrequently, then the effect is probably marginal. I would also suspect that those who would be inclined to buy large amounts of SC would either be typically motivated to buy up to retain (eg: Gold) which makes sense if one might fall a bit short, or those looking to earn high status for a spend without putting one's BIS. A product like the HSBC Star Alliance card is aimed at these folks I suppose (though the status comp is only for the first year iirc). I guess if those kinds of folks have the coin to buy in like that, they're going to spend more on travel anyway.
I'd prefer an option to buy up to retain status, or perhaps make the next level if close - but to a certain limit (eg: 50 SC short of Silver? ok. 100 from Gold or 200 from Plat say then have a buy in, but not 500 from Gold). With the UA example linked in the article, for example, the buy up prices for 2024 weren't exactly attractive to most for the levels, so you'd have to really want it (and have the coin) but it could be an option (or just formalising more the seemingly on and off "x points to retain Gold/Plat" offers we've seen QF do)l
Basically, I don't think high tiers of status should be available for those with the spending power to get there. We already have ways to make it easier (DSC) but even those require one's butt in metal tubes - so I'd prefer it stay that way - but I do see a place for a limited set of options for one to bup to retain or advance a level if close.