This is not like those other things.

We have shepherd's pie (lamb) and cottage pie (beef) and fisherman's pie (fish). They're all constructed in much the same way but the name refers to the contents.

It's just a misunderstanding and it's not important but there is a real non-obsolete reason these dishes have the names they have.

Almost all of them extend from an action that still holds true:

• Roll down windows - you still get manually operated windows, and the motor rolls in electric ones.
• Dial phones - the verb has a separate definition to the noun.
• Use a clicker - not sure what you mean here, but things do still click.
• Write on computers - a piece of writing can be typed or hand-written. It's about making a marking on a surface.
• Blackboards/chalkboards/whiteboards - the first two are generally wrong, whiteboard is the only one that would apply to a digital surface.

I'll throw in another one:

• Windmill - they're not windmills, they don't mill anything. They're wind turbines.

Some of these terms stem from marketing people, who are only a couple steps down from estate agents in terms of the evil they bring into the world. This should not be celebrated.

Many of these can be considered acceptable, even in the ways that they're wrong, but it's still acknowledged that they are wrong. With biscuits, people think they're right.

Biscuits are established because people were wrong. That doesn't mean people today are right.

Your example of plumb and level doesn't work, because plumb is still considered the correct term for vertical alignment. People will generally know what you mean when you say level, but the other term is still considered more correct.

"Biscuits" are nice, but they're not really biscuits, they're savoury scones. Meanwhile, most store bought long shelf life cookies are biscuits, in spite of being sweet, while fresh cookies are generally not. Similarly, tomatoes are fruits, not vegetables.

You can say it the wrong way all you want, but when it goes against the core definition it can never truly be right. I literally can't stand it being so.