Haha, well I can see you're obviously a huge fan of Decathlon. I will concede they do more stuff well than I previously mentioned. As you pointed out the clothing is well designed. I also have a pair of Decathlon climbing/hiking trousers which have served me really well too.
They do hit the middle of the price point range with much better features than the totally cheap (and rubbish) gear (like the stuff you get at Lidl supermarkets). I wil tip my cap to them for that.
Still, when it comes to high performance equipment, I personally wouldn't rely on Decathlon. When I feel that performance is super important, I will prefer to pay a premium for additional features and/or better design.
A good example is climbing shoes. I typically buy La Sportiva shoes, and that's because I know the rubber types (XS Edge or XS Grip) work super well, certain models fit my feet really well, & the performance I get from the shoes is just worth it (for me).
Side note: since you get it shipped to the US have you ever been inside a Decathlon store??? It's wild how big they are! You could get lost for a whole day inside ๐๐๐
Well, I do believe that all safety gear purchased from Decathlon is fully certified and rated for the application. So that's good! & it's not the same as buying sketchy uncertified gear from Amazon, or AliExpress (or whatever).
But sure, there may be differences in the function between Decathlon's own brand Simond and (for e.g.) Petzl, or Black Diamond, or DMM, or Edelrid.
Weight is usually a big one. Some of the top manufacturers of climbing hardware really have put it a tonne of engineering to shave off weight in their designs. A few grams on 1 carabiner can add up over a full rack. Other things are like gate design & gate action. Top of the range carabiners often have a nice gate action, and it's not uncommon for people to have a preferred style of gate (i.e. wiregate, Vs solid gate) to make clipping the rope more fluid.
If you are mostly sport climbing, saving weight might not be a big factor, and in that case maybe there's less to differentiate. However if you're trad climbing, or multi-pitch climbing, or even big walling, saving weight might be a huge consideration.
So all in all, it depends ๐ it can really help to get out with friends and try their gear to see if it makes sense for you. I also watch a fair amount of gear reviews on YouTube, or read gear reviews online.
But yeah, all in all, I do think Decathlon is great for certain items. But I also think it's worth paying extra for those items which you want to function really well (and this can be pretty subjective).