Homebrew Feat - Modifier - Expertise - Choose a Skill or Tool Missing?

Why can't you choose the option "Choose a Skill or Tool" for the Expertise modifier like you can for the Proficiency Modifier when creating a homebrew feat?

Probably because tool expertise wasn't a thing before artificer.

Rogue? Yes it may be a specific tool, but it was a thing.

I also just wanted to point this out so hopefully it could be resolved.

Quote from mouse0270 >>

Rogue? Yes it may be a specific tool, but it was a thing.

I also just wanted to point this out so hopefully it could be resolved.

 Ok fine: *except theif's tools.

Try mentioning it here: https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/21916-what-additional-modifiers-would-you-like-to-see