[peer2pay]

80% SoH is the de-facto industry standard for EoL/replacement. Mostly because after that you will eventually get a "knee-point" in your degradation curve at which operation is risky and largely inefficient.

Without knowing specifics, your MBP might have had issues with an individual cell such that initial capacity dropped significantly until the cell was disconnected.

[vasco]

Enough cycles and you get a free pillow so the risk comes with rewards sometimes!

[formerly_proven]

I've seen several laptops start out in the 90-95% SoH range, drop off quickly to the mid-80s and stay there for a very long time. Similarly for iPhone batteries, they go below 90% pretty fast, then each % off takes longer and longer until they actually start dying. Maybe that's due to different baselines though, BMS of laptop batteries normally refer last-full energy to the design energy, which is probably just a fixed value in an EEPROM and might not ever be reached due to a more conservative charge cutoff and tolerances.