If the higher levels give the player access to better or at least specific skills or equipment, then do show the level. At least when we loose to a higher level guy, we will know it wasn't entirely our fault. And when we win against a beginner, we will know it wasn't such a big deal. It also serves for searching for games with more people around your level. It works like this in AC3 and it's very good.
However, I would actually prefer if the levels didn't make a big difference in the players raw power. I think we should be able to get what we want early one, kinda like, getting full power in one play style, then, later, with a bigger grind, getting more options in case we want to diversify. Kinda like Killzone 3. Kinda.
More specifically, if there is a type of stat, like Booster1, and this stat has a bunch of options, when I can get a Boost, I should be able to choose amond ANY option (instead of waiting until I get to a high level, to be able to get such an option). However, being able to get my second option, should require a bigger grind. Then I'd choose it freely, again. Then the 3rd would require an even bigger grind... and so on.
If the skills are truly balanced, why is it I can't get this one before I get that one? This is something extremely dumb that most MPs have. That's what really discourage players, the difference in raw power between people who has played for more time and those who are beginning. Me angry.
You can add a lot of aesthetic stuff to higher levels, to keep things interesting even for those who already got their favorite skills and stuff. Don't put a freaking situational awereness to make people aspire to that level. That's a cheap trick.
I wouldn't actually care much about kill per kill, unless the guy killed me because he has a booster I can't have. Then I could be curious. But, as you said... the skill level... no, I wouldn't care. At least not as victim. But I would surely be more excited by doing well against guys who had played for a long time, as opposed to hunting noobs. Hunting noobs can get you soft.
The thing about the rage quitting really depends on the rules. Some games still let the guy walk out of the game takig the points he won. Other games don't. There are many ways to punish and shame rage quitters. I don't think hiding stats is the best solution.
If they have what I consider a good MP progression where there is a power balance between noobs and veterans... then they could hide the stats all they wanted. I wouldn't care.
And about numbers being a psychological hazards to the MP... I'd say: only if they're not used well. Using them well is surely better than not using them. The points ar the best way for the Devs to manipulate the players into playing the game as the Devs think the game should be played. Battlefield 3 and AC 3 did this better than any game. In one the kill points are usually only half of all your points, cause there is so much teamwork stuff that justly rewards you. In the other, style matters more than the quantity of kills... I think it's genious how they make it work. K/D means next to nothing in AC 3. It's brilliant.
Not trying to just be negative but I think it's safe to assume there will be ranks in TLOU's Multiplayer. It stays true to current gen's multiplayer (something we know Naughty Dog loves to keep up with), it wouldn't be right without them. Now that's not my opinion but it's just how it works.
I'm pretty sure we've all seen te pre-order bonuses for multiplayer
• Multiplayer In-game Currency Boost
• Bonus Multiplayer XP
• Melee Attack Booster Pack
Seems like they're attached to a ranking system to me. Maybe you'll be lucky and they will take out leaderboards but they will keep numbers next to our names no doubt.