Some time ago Valve merged Solo and Party Ranked together with the intention to promote Party play. It did however result in the opposite and created more problems than it fixed.

In my opinion, putting Solo and Party Ranked together was the worst idea Valve ever had. If i remember correctly, Valves intention was to promote competitive play but ever since they put both gamemodes together all stacks i played in and regularly saw in my friendlist all stopped playing together. Sometimes i maybe see a duo stack but before that change my friendlist was full with 5 stack parties and other stacks that used looking for party thingy to fill up their stack, I haven't seen anyone use this feature in like a year now however.

I never understood why Valve decided to merge Solo and Party instead of simply making Party Ranked better. This was like the laziest way possible and it didn't even work out. All it did was not wanting people to lose the MMR they gained in solo and create paradise on earth for boosters.

My suggestion

1. Separate Solo and Party again
2. Have 2 different set of Rank Icons so Party Rank does not "devalue" Solo Rank.
3. Increase gap between Ranks so that for Immortal Party Rank for example you would need 7000 MMR
4. Add Quests that promote playing together. Like whenever you win 10/50/100 Games with a friend you both get extra Shards.
5. Please finally add proper Seasons with Seasonal rewards. I know many will here say "sEaSonS aRe sTuPid" but there is a reason why competitions have seasons that reward you by the end of it based on your performance.