Lost the crust but gained all the flavor, so totally worth it.

Years? That seems like a huge stretch. Beginners might mix up pyrite and gold for a bit, but a simple streak test tells you in seconds. Calcite and quartz can look similar, but vinegar bubbles on one and not the other. If someone's actually using a field guide, they'd figure it out way before years pass. Your point about tools is fair, but the time frame is just over the top.

Wow, I always thought attic cleanouts were dull, but this idea is brilliant!

Using the Merlin app last month, I correctly spotted a Blackburnian warbler by sound alone. My phone did pick up wind noise, but the app still sorted it out and gave me the right ID. Without it, I would have guessed wrong because the call mixed with city sounds. Sure, experienced folks can tell, but for beginners like me, these tools are a game changer. They cut through the confusion when your ears aren't trained yet.