This definitely counts into why support role is unwanted by many players, supports sacrifice everything for their team and it just result in themselves being extremely weak as an individual (RIP 
who got deleted despite having ult on with full hp) and feel underwhelming.
KłedGod1 votesJunglers tend to fall behind in the early game compared to solo laners also. I dont think its 3-5 levels but usually 2-3 then they slowly creep back in and catch up
The Deckowner1 votesJunglers are some what fine because they have constant source of exp/gold income which they don't share with others.
but supports literally have nothing.
(just watched a LCS and i realized the 10k gold lead team's 0/1/6 support is 4 levels behind enemy 1/3/2 mid laner, there clearly is an issue)
KłedGod1 votesbut in LCS the support roams and double jungles for most of the early game. thats the reason why. if anything making supports get bonus exp for using there support item passives would be a good new feature.
Meep Man1 votesFor me it's usually 2-3 but thats still around your area.
Curling Veigar1 votesIt's simple.
No CS? you lose experience.