Unfortunately they have to do this if they don’t want to lose the trademark. You can’t trademark something if it’s deemed to be of common use. Of course if your trademark is a color then this can be quite difficult.
That's what the lawyers say, anyway. Thousands of companies manage to do business for decades without egregious trademark actions.
Company A has a trademark. Company B creates its own product (perhaps trademarked as well) which is somewhat similar to Company A's trademark but in a sufficiently different product space that a lawsuit by Company A would seem potentially frivolous. Company B then grows its business over several years, starts moving into adjacent product categories, and ends up with a product that now could get mixed up with Company A's. Company A sues Company B, but Company B argues that it has invested a lot into its own brand, and Company A should have been policing its brand years ago to make sure Company B doesn't end up investing in a brand that Company A would end up considering infringing down the road.
I'm not convinced that their behavior was either justified or effective.
I hear a lot that bad things could happen if companies don't bully people over trademarks, but I also see lots of companies being good neighbors and doing fine regardless. Are all of these companies both cursed with incompetent lawyers and blessed with uncanny luck?
edit - sorry, mistake, I meant trademark. I didn't know that wording mistakes were downvoted so harshly.
I am amazed they can even claim a trademark over magenta, is that better?
copyright protects the right of an author not to have their work copied (without their permission)
patents protect inventors from having their inventions used (without their permission)