Having read about airlines potentially penalizing those engaging in "throwaway" ticketing to get a lower fare than would otherwise be possible, I wonder if this is anything the airlines would view negatively.

I regularly fly JFK-BKK in J. On the return leg of a trip last year, the airline was unable to accommodate a change without a huge fare difference (ahem JAL), so it was cheaper to sacrifice that return and buy another r/t ticket originating in BKK on another airline(ANA, far more flexible), leaving me with an extra JFK-BKK ticket I'm able to change easily.

Now I'm going to use that ticket to go back, and purchased another ANA r/t ticket originating in BKK, leaving me with another unused JFK-BKK I'll schedule far out and change once I settle future plans.

This has worked well for me since the same tickets originating out of BKK are often significantly cheaper than those originating from JFK.

I don't see how this could be seen as abusive, but I've saved thousands now, and frankly I feel like I've stumbled across some forbidden practice, lol.

ANA has a notice on their tickets about possible cancellation of a ticket if they observe something they consider abusive use, but don't go into further detail than that.

Not abusive at all. Very common practice. Nothing to worry about.

Much appreciated

I think ANA and others might get upset if done on the same carrier (usually to circumvent fare rule restrictions). This is two different carriers, so no issue.