The typical Ottoneu dynamic is different, though. It’s usually contenders paying cheap players for expensive (but still potentially valuable) ones, to an owner that’s not charging any premium for the loan.
The Indians paid a premium to get Miller because he’s affordable on his current deal. They’ll get a supplemental for him, but they were in no position to pile up a bunch of guys on $10M+ contracts and then get to trade them in the offseason.
40/400 in the offseason may be too restrictive, but as has been noted, being able to add a bunch of marginal surplus guys that can still be traded before the next season is hardly selling out your future. You can recycle your short term assets season to season in most leagues, and stay on top.