I've run D&D games for decades with 2 or 3 PCs. No sidekicks, no hirelings, just the party members.
It requires a little more out of the box thinking that people like to pretend D&D allows, but it's not any kind of a problem.
I also run DCC games with only 2 or 3 PCs (and will be doing so again on Sunday), and I've run them with as few as 1 PC. Again, no multiple characters per player, no "sidekicks," no nothin.'
I think that many people get very wrapped up in the idea of character classes being a list of things a character can do instead of merely a way to classify a character concept. Nothing prevents a character from trying anything, and a chatty, seductive barbarian can be every bit as rewarding as a dumb-as-nails wizard or a moody, taciturn bard.
These days my recommendation for anybody looking for a game is DCC. It's fast, flexible, easy, inventive, and you can get started with free rules form the publisher. Hard to beat IMO.