You absolutely can. A good portion of popular trackers have periodicall open signup events. Torrentleech has fairly often open signups. It's big so it isn't that easy to build up your ratio when you're a drop in an ocean, but when you do it can open doors for some more prestigious trackers, although TL should be enough in 99% of cases if you aren't into some (less popular) niche content. Watch r/opensignups on reddit if it's still alive and soon enough you'll be on too many trackers.