Maybe some of you are playing it wrong.
I grind for 8 hours on 19 Apr and already got both Taroth alpha & beta armour set, all costume armours, both Taroth & Samurai palico set.
General Gathering Hub strategy for good loot within shortest time spent :
1) Use the search Online session filter, set to "Experience" & "Kulve Taroth" preferences.
2) Join the resulting session populated with at least 13/16.
3) Check the current pursuit level and the current available siege squad pursuit level.
4) If the current pursuit level is 3 or 4 and the available squad pursuit level is 1, don't waste your time joining them.
5) Wait for someone to start a siege at current level 3 or 4, then join them if members are HR 100+.
6) Once you complete the round (not expected to break the horns here), your rewards level will jump from 1 to at least 8 pursuit 3 or level 10 in pursuit 4 depending on the hub's siege progress.
7) Wait until someone started pursuit 5 or 6, then join them if members are HR 100+.
8) When the horns are broken by other squad, your rewards level should be around 15 or even the max 17.
9) If your squad manage to break the horns, then if you are lucky you can carve max 2 melded weapons per horn piece.
Bonus) Get your forging gem from the carving horn plating drop anytime during any pursuit level. Don't rely on the end quest rewards, because it is super rare when it happens.
just dont be selfish, if everyone playing like this, there is no more Level 3 above for you join too. They are start from Level 1 too.