How do you make a meter relative to the left side of the previous meter?

[balala]

But i'm not sure why is it missing in Rainmeter?

Because it is not so simple, in my opinion. For instance what if the previous section is not a meter, but a measure? Doesn't look a feasible approach.

[pul53dr1v3r]

Because it is not so simple, in my opinion. For instance what if the previous section is not a meter, but a measure? Doesn't look a feasible approach.

yes, i had it in my mind and skins creators that use the option should know what's before the meter or don't use it if not sure. When i was a big noob (bigger than now) , i didn't use a lot of the built-in variables and other option, but with time it changed.

Also, most of us put all the measures before meters. It's kind of neater than mixing it up with one another.

[balala]

When i was a big noob (bigger than now) ,

I don't think you are a noob. Not anymore...

i didn't use a lot of the built-in variables and other option, but with time it changed.

Yes, I suppose many users are avoiding using them, me also did for a long time, but as you said, after I while I realized they are very useful, so finally have started using them.

Also, most of us put all the measures before meters. It's kind of neater than mixing it up with one another.

Yes, most of us, but not everyone. This is not something absolutely needed to get the code working.
But if you think this would be a useful feature, add a post to Bugs & Feature Suggestions.