People on both sides seem to be asking for "real numbers", so here's one more stab at it. This is the damage per Attack action by an archer fighter, with various combinations of feats and bonuses vs. various target ACs. This does not give the fighter any benefit from magic weapons or subclass abilities (both of which tend to make CE+SS even stronger). This also ignores any accuracy benefit from Sharpshooter (SS) allowing the fighter to ignore cover or range penalties or Crossbow Expert (CE) ignoring disadvantage in melee. So overall I think this is biased somewhat against CE+SS compared to actual play.
For the target ACs, I chose the DMG-recommended AC for a monster with a CR of character level - 2, as well as -4 AC and +4 AC from there.
The fighter is a variant human starting with 16 Dex and the Archery fighting style. The versions with Crossbow Expert use a hand crossbow; those without use a longbow. The "no feats" version chooses a non-combat feat and then uses all ASIs to increase Dex until it's capped at 20. The single-feat versions start with that feat and then use ASIs to increase Dex. The CE+SS version has both feats by level 4 and then uses ASIs to increase Dex. Versions with SS are always using the -5/+10.
The math includes all relevant factors and probabilities, including crits. Damage is rounded to the nearest 0.1.
Code:
No feats CE only SS only CE+SS CE+SS+Bless CE+SS+Bless+Adv No feats+Bless+Adv
Lv 4, AC 9 8.3 14.6 14.1 23.5 27.6 32.6 8.9
Lv 4, AC13 7.0 12.3 10.4 16.9 21.0 28.9 8.9
Lv 4, AC17 5.3 9.3 6.7 10.3 14.4 22.7 8.3
Lv 6, AC10 18.5 24.8 31.7 39.9 46.5 52.5 19.8
Lv 6, AC14 16.6 22.2 23.9 29.4 36.0 47.8 19.8
Lv 6, AC18 12.8 17.1 16.1 18.9 25.5 38.9 18.9
Lv11, AC12 27.8 33.0 44.6 56.2 65.5 74.0 29.7
Lv11, AC16 23.5 27.9 32.9 41.4 50.7 67.3 29.5
Lv11, AC20 17.8 21.1 21.2 26.6 35.9 54.7 27.6
Even against the high-AC targets with no attack bonuses (Bless or Advantage), using the -5/+10 from Sharpshooter is always an advantage. In extreme cases adding CE+SS gives almost 4x (366%) the damage as not having the feats (32.6 vs. 8.9 damage for an AC9 target at Lv4 with Bless and Advantage).
For targets of typical AC, it looks like CE+SS gives a bit more than double damage compared to a baseline longbow archer if you assume that parties tend to generate more situational advantages for themselves as they increase in level.
For example:
At level 4 vs. an AC 13 target, CE+SS averages 16.9 damage vs. 7.0 damage without feats.
At level 6 with Bless vs. an AC 14 target, CE+SS averages 36.0 damage vs. 18.3 damage without feats.
At level 11 with Bless and Advantage vs. an AC 16 target, CE+SS averages 67.3 damage vs. 29.5 damage without feats.
It's true that Crossbow Expert also contributes significantly to damage, but SS is the larger component at higher levels and/or when you stack more attack bonuses.