Again, no it doesn't. The penalty is always there unless you are also targeting an AC that you would only miss on a 1 normally, and would only miss on less than 5 numbers higher while taking the penalty - to phrase that clearly, unless you only miss on a natural 1 normally, and only miss on a natural 1-5 when taking the penalty, it is still a -5 penalty both in name and in effect.
Again, you are phrasing something in such a way as to make it an untrue statement even if what you are meaning to convey were the truth.
I absolutely can say "working as intended" even though extra damage from other sources is less prone to amplified effect through teamwork.
I can do so because I can see that teamwork as being intended to make each option put into it more powerful - because that's how to encourage teamwork; you make it actually work and be worth something.
If you miss more often and deal more damage when you hit, you have to first deal all of the damage you would have dealt when hitting more often before you start getting into the territory of dealing more than you otherwise would have.
So let's go ahead and put some numbers to your claim here and see if it holds true as you have chosen to phrase it: 40% of attacks with the feat benefit hit vs. 100% of attacks without it, that means that the attacks with the benefit of the feat have to do 2.5 times the amount of damage in order to match, and more than that to pull ahead - so the +10 damage from the feat needs to be greater than 1.5 times the base damage of an attack. Which means the base damage of an attack has to be lower than 6.6 (repeating).
Which is not the case with any two-handed weapon I'm aware of unless the character in question has a +1 or lower strength modifier (since two-handed weapons have 1d10, 1d12, or 2d6 damage).
So your claim is shown as being factually inaccurate - so we can't reasonably use it to determine how we feel about whatever the actual case of the feat's performance is.
Sharpshooter + crossbow expert was the example I used and the math with that example assumed no buffing being used.
40% is also a low ball thing my players usually only use the feats if they have a 50% chance or better to hit (after the -5). This means buffed or combos like the war cleric + great weapon master (an out right +5 to hit +10 damage).
Its the degree of the team work required I doubt they expected people to very few resources to enable a +10 damage across the board starting form very low levels. A single source of advantage mostly eliminates the -5 penalty and combined with the archery style in effect gives you a bonus to hit and +10 damage.
Your math is wrong when it comes to in game examples I provided. Advantge+bless for example enables those feats to function at an absurd level of power worse than someone taking advantage+bless to hit and not using those feats.
Mathematically advantage is around a 4.5 to hit, bless is a +2.5 so in effect you have two options if you are under those conditions.
+7 to hit OR
+2 and +10 damage.
OR (with sharpsooter)
+9 to hit or
+4 to hit and +10 damage
Those bonuses are above and beyond what you already have to hit. This is in a real world game of D&D against an unknown AC combined with multiple attacks. At mid levels (5+) the base to hit is usually a minimum of +7 (+3 prof, +4 from stat) or at worst +6 (at best +8) excluding magic items (which PCs usually have if you have played 3pp or WoTC adventures).
In effect you have at least +11 to hit and +10 damage (technically +6 to hit with advantage) which functionally means 60% or more chance to hit through to AC 18 80% at AC 14 and monster ACs in 5E do not tend to be very high.
If 3/5 attacks on average hit for 1d6+14 damage vs 1d6 +4 5 attacks hitting for 1d6+5 damage is an average of 32.5 damage vs 52.5 damage with 3 attacks hitting (and the more you can shift that to 80% with the -5 included the more absurd it gets).
In a real game we have hit AC 22 and 23 with the -5 things (bless, prone, bard dice, higher numbers to hit than these assumed defaults etc). Once proficiency bonus hits +4 or higher and scores get maxed at 20 for example those feats are the gift that keep on giving (along with bless).