The method `User::isBlocked()` attempts to answer two questions:
# Does the user have a block?
# Is the user prevented from performing this action?
The method can answer #1, but it cannot answer #2. Since `User::getBlock()` can also answer #1, this method is redundant. The method cannot answer #2 because there is not enough context in order to answer that question.
If access is being checked against a `Title` object, all access checks can be performed with `Title::userCan()` which will also check the user's blocks.
If performing all access checks is not desirable, using `User::isBlockedFrom()` is also acceptable for only checking if the user is blocked. This method does **not** determine if the action is allowed, only that the user's block applies to that `Title`.
If access is being checked without an existing `Title`, `User::getBlock()` can be used to get the user's block. Then `Block::appliesToRight()` can be used to determine if the block applies explicitly to a right (or returns `null` if it is unknown or `false` if explicitly allowed). If the user is creating a new `Title`, but the text of the title is not yet known (as in the case of Wikibase), access should be checked with `Block::appliesToNamespace()`.