I've noticed that there's only a "filter, and display filtered"

What I am suggesting that you be able to "filter out" planets when sorting them.

for example, if you want to see all planets EXCEPT the ones you own, you would be able to filter out planets owned by you and only see planets not owned by you.

-1

we already have the unoccupied tab and the enemy-occupied tab. it is not hard to toggle between these to do what you want.

you counter example is based off my example.

I gave an example of why you would want that

you can filter out more than one type of planet if you want.

I've found that having this function would make my life sorting planets much easier

what kind of negative effects would this have?

it's been many years since i've done logic programming for my electrical engineering classes, but let's see if i can explain simply:

the current filter IN allows any items matching ALL of the terms to pass through, so you can use the filter to narrow down your list of results.

a filter OUT would be crippled as soon as you add a second term as anything that does not match ALL terms would be allowed to pass ... adding a 2d term would mean that NOTHING would be filtered. the programming required to treat each term separately for a filter OUT versus inclusively for a filter IN is a much greater hurdle.

the negative effect is on programmer time as this is NOT a simple thing to do unless you allow boolean operators into your search parameter ... which opens up a whole other can of worms in terms of avoiding scripting exploits. try doing something like this on google without using multiple NOT parameters.