They do. You're notified when battery health is either unknown or reaching EOL. It points you towards replacement, not upgrade.
"If battery health has degraded significantly, the below message will also appear:
Your battery’s health is significantly degraded. An Apple Authorized Service Provider can replace the battery to restore full performance and capacity. More about service options…"
"If battery health has degraded significantly, the below message will also appear: Your battery’s health is significantly degraded. An Apple Authorized Service Provider can replace the battery to restore full performance and capacity. More about service options…"
https://support.apple.com/en-us/101575