Although you can bulk modify a number of transactions to set the same Category for them all, it can be an onerous process if you have imported a large number of transactions from your Bank Import.
For example, If I purchase my groceries from ASDA/Walmart (to cover both sides of the pond), I would like to set the Category to Groceries for this Payee once and have the link maintained automatically for future entries.
Going forwards there would be a reducing task to add the 'linkage' for future un-linked transactions and any transactions that are incorrectly categorized can then be edited where required. This would be less work than having to categorize every entry.