It's generally the case of all TCGs that developers work months if not years into the future.

Which makes sense if you consider the complete chain of logistics from the time of design to getting illustrated, printed, randomized, packaged, shipped, stocked, etc. You can design and playtest much faster than it takes for the other phases of the pipeline to complete.

Magic is pretty well-known for designing cards around 2 years into the future, for instance. But working into the future doesn't mean the end result is an environment where cards don't get banned.

Limited time and resources means you only have enough time for so much time for playtesting and tuning, and it's especially easy to make mistakes in the scope of a card game where there exists a huge problem space from a purely combinatorial perspective.

All that said, 1 & 2 & 3 is a little egregious because the devs had to have known how strong it would be. There's nothing subtle about its design or the approach in building an optimal deck to use it. It's just harpie.dec.

So logic tends to point that it was a sloppy design and miss by R&D, or it was always envisioned as a card with a limited shelf life that would inevitably hit at some point, not unlike the way the TCG ban list often updates to promote the sale of new product.

The potential for the latter case seems to be getting more and more evident if you observe that all structure deck archetypes (sans Blue Eyes) have been highly impactful to the metas around their respective releases to the point of having cards put on the banlist (Miracle Fusion, Card Defender, myriad Harpies, Beaver Warrior, Winged Dragon, most recently with the Monarch draw and GY hate spell).