If you see a collab and notice that the idea already exists, don't write something like "You mean something like this: ..." or "There is already an app for that", that's just fucking demotivating. Don't be an asshole.
If someone wants to do something and has a motivation for it, just write "Good Idea!". It helps this someone to be happy about something they have come up with!
Make him smile!

Thank you for listening!
Now go on devRanting!

<@norman70688>
Yes. Just keep it for yourself.
Maybe this guy even makes a better version of it!

Well you could use the other product for analyses. You can always learn something from competitors.

<@MisterArie>
You're right but imagine your have come up with a big idea under the shower and really want to fucking do it! Only to find out that there is already something like this...
Already made this experience twice and I hated it.

<@Jilano>
Hmm yeah but I made the experience that when looking at similar projects, you begin to find features there you thought were unique and then more and more feel like you're doing useless work.

I can accept this only so far as being courteous while pointing it out.

1) If someone points out existing similar software it may actually be used as a reference. Which may end up being useful for the poster

2) In most established techs, most things that can be made are already made. You can post literally anything in JavaScript and unless it's a PhD project, I can guarantee it exists in some similar form.

If you're going to interpret someone posting similar stuff as demotivating, you're not gonna be able to build much. Like at all.

3) In rare cases where an idea is like really bad or if we know for sure that it won't work, I bloody well expect a community to tell OP that it's bad. I'd rather assume a minimal amount of maturity in accepting negative comments, rather than favor propriety and let OP run towards a dead end. This hasn't ever happened that I've seen but the principle counts.

friends don't let friends reinvent the wheel