Agreed on never being the one blocking merges, but for the merging party, “if people don’t prevent merges” is such a huge caveat that I think attempting a zipper merge at a lane ending at any appreciable speed is impractical at best and downright dangerous at worst.

If everyone is traveling slow already, failing to merge quickly at the lane ending isn’t a huge threat to safety and just a slight hit to efficiency. Most merges I’ve experienced are probably in the 40 to 80 mph range though. In that case, you absolutely do want to take the first decent merging opportunity you can, because waiting to do it until the lane ending can have huge safety and/or efficiency consequences if another good merging opportunity doesn’t open up at speed.

Also, I’m pretty sure zipper merging was mentioned zero times in driving lessons and tests where I’m from, so you should basically just assume other drivers don’t even have it as a concept. If you’re from somewhere where more people practice it regularly, then I can see why you are more encouraged to enforce it as a baseline.