Here's why I say the digital tools were vital for 4e for me - and other groups I know. (Of course, if you played or currently play without the tools, I'm not trying to disregard your experience.)
How many different resources did you use to create your character? Maybe Player's Handbook 1 for your race, Player's Handbook 2 for your class, Martial Power for a few feats and powers, a few magic items from Adventurer's Vault, etc. (you see what I'm getting at). And what do you need to record to know how to use the feat or power - like a static bonus or weapon damage - or is it a paragraph of text and different effects? And when you level up, what do you need to change your bonuses on - every different attack, damage, defenses, hit points, bloodied value, healing surge value, etc.?
As a DM, you can easily adjust monster stat blocks in your head to level up or down to appropriately the challenge the party? Sort through monsters in a comprehensive database? Search for magic items across something like 10 different sources? And you have access to all the errata?
4e was designed to be played with these tools. Don't believe me, watch the original marketing videos. Without them, I think it's a clunky mess. With them, it's probably my favorite edition of D&D.