Dart SDK, can you please clarify the purchasePackage() sample code?

Hello, could someone kindly explain why we should check entitlements.all isActive after a purchase before unlocking the feature (see code below) ? My points are:

1. If purchasePackage() didn’t fail, it means that the purchase was processed successfully and this should be enough to unlock the features associated to the purchase.
2. Checking isActive of Entitlements doesn’t make sense in the case where Entitlement has several consumable products (ie. boost_1, boost_2, boost_3) which can be purchased multiple times (so for example , user might have 3 active boost_1, 1 active boost_2, 5 active boost_3, etc). In that case, using customerInfo.entitlements.all["my_entitlement_identifier"].isActive might lead even to wrong outcome. Am I missing something?

try {
CustomerInfo customerInfo = await Purchases.purchasePackage(package);
if (customerInfo.entitlements.all["my_entitlement_identifier"].isActive) {
// Unlock that great "pro" content
}
} on PlatformException catch (e) {
var errorCode = PurchasesErrorHelper.getErrorCode(e);
if (errorCode != PurchasesErrorCode.purchaseCancelledError) {
showError(e);
}
}