It very much is average for a d10 is 5.5, agonizing gives +5 with 20 charisma averaging to an extra d10 worth. . The dmg 284 table has:And some spells remain effective even without upcasting. Ultimately how effective warlocks end up being compared to other casters varies from table to table, but I think the common consensus is they trend a little on the weak side.
That’s just not the case. Eldritch Blast is tuned like a Fighter with a heavy crossbow and no additional resource expenditure (such as action surge or superiority dice). It’s strong for a cantrip, yes, but it is definitely not tuned to be the Warlock’s only source of damage.
1st 1d10
2nd 2d10 Level 1-4 agonizing blast is here (1d10+an effective second 1d10)
3rd 3d10 add repelling & you probably get here for a 5 foot knockback on top
4th 4d10 Level 5-10 agonizing blast is here. (2d10+an effective second 2d10)
5th 5d10 add repelling & you probably get here for a 10 foot knockback on top
6th 6d10 Level 11-16 agonizing blast is here. (3d10+an effective second 3d10)
7th 11d10 add repelling & you probably get here for a 15 foot knockback on top
8th 12d10 Level 17+agonizing blast is here. (4d10+an effective second 4d10)
9th 15d10 add repelling & you probably get here for a 20 foot knockback on top
Eldritch blast is very much not the equivalent to a heavy crossbow because a heavy crossbow has the loading property, does not deal force damage, does not have a knockback, & does not scale the fighter extra attack based on character level like EB.
That's a lot of ifs balanced around "your the gm, you fix it & you figure out where it needs to be & you make it work" piled on a GM by d&d5e. With the system structured mechanically to almost guarantee that players can successfully rest without gm fiat simply disallowing it things are almost certain to swing in a direction where short rest classes are problematically overly goodYMMV. If this is the case at your table, yeah, warlocks are going to be about twice as strong as expected. If you get fewer then one short rest every other encounter, warlocks will be weaker. This is also the case with every other caster with the frequency of long rests. Turns out, resting as a limitation of power can become unbalanced pretty easily if the actual frequency of rests doesn’t end up meeting the expectation.