savageorange said:
(I suppose the other side of the argument might be : "it's not any more confusing than blacklist rules already are". On the other other hand, there is generally exactly one way to correctly write a given blacklist rule, not multiple ways.)

There are multiple ways to correctly write a blacklist rule. Before grouped tags, blacklist actually allows more combinations than search (for non-metatags).

Since you have multiple lines at your disposal, you can represent tag1 ~tag2 ~tag3 as
two lines,
tag1 tag2
tag1 tag3
(You can unwrap all OR operators in this fashion, and it allows you to prefix the NOT operator on tag2 and tag3)

Another example is tag1 -tag2 can be written as ~tag1 ~tag2 -tag2, and it can also be written in two lines as
tag1 -tag2 tag3
tag1 -tag2 -tag3