If I understand correctly, the OP is suggesting that phpBB comes with several posting editors installed as standard.
For example, one may be the native plain text editor supported by BBCodes we currently have. Another may be something similar in nature to WYSIWYG or equivalent.
I think the comparison to captcha relates to how easy it is to choose between those options. Inasmuch as there are 4-5 captchas installed by default, these can be easily selected from a drop-down menu in ACP.
@OP: The suggestion may gain better traction if you expand on what an alternative editor should include, and why it would be more or equally beneficial to the one that comes installed by default