I say this on every "returning player" post: I came back from a long break and ignored all the advice to restart. I had a few G10 characters (no legendaries because they didn't exist when I left), and surely that wasn't worth throwing away!
I really, REALLY wish I had. I just started breaking top 10 squad arena in the last month or so, after hammering away for a year and a half, and it won't be a regular occurrence unless the Mod Gods decide to be very generous.
I don't like arenas much either, but the folks saying you need crystals to progress at a good pace are right. Without a decent amount rolling in daily, the time it takes to farm and gear stuff up is dramatically longer - even more so now that g13 and relics are a thing- meaning you fall further and further behind the curve.