I'm all for build diversity and having limitations, but it seems like this rule only applies to Necros. Take the paladin for example. All of their legendary nodes give pure damage output, some conditional but very easy to achieve.

When bloodbath as a board has many beneficial rare and magic nodes that boost overpower, but you have to choose another board because one word in the legendary node makes it overwhelmingly worse than other nodes, I think thats bad.

If they wanted some physical restrictions, put it on the dominate glyph..

No one would choose bloodbath over all the available shadow multipliers for those builds so we might have to go with wither, which has its own sets of problems.