Does using a less common opening make you a stronger player? I want to ask about whether using and adopting a rarely used opening makes you a stronger player.

I just started playing online chess (Lichess) a year ago, and as a beginner, I used to play the common 1.e4 as the opening in all my games. I found that by doing so I was stuck around 1300-1400 (below average rating at the website). Last month, I read an article about different openings, and suddenly switched to regularly use the 1.a3 Opening (usually starting 1.a3 2.b4 when white, and 1.h6, 2.g5 when black, using the bishop to occupy the diagonal), and my rating suddenly went up to 1700-1800, and stayed there. I found that by using this opening made the middle-game much easier to play, making my opponents make more mistakes than usual compared to the typical 1.e4. 

Is this normal? Or does it happen to anyone if they suddenly want to switch to a different, more rarely-used opening?
In general, less common openings tend to give weaker opponents issues, since they have yet to properly grasp many fundamental ideas of opening play and middlegame strategy, and if they don't know the concrete lines they may very well end up completely lost from a nonstandard opening position.

But a nonstandard opening doesn't make you into a stronger player just because you have good results on lower levels. In the end, you will hit a plateau with the nonstandard opening as well, when your opponents get sufficiently strong. Don't forget that these nonstandard openings are nonstandard for a reason: with correct play from your opponent, you're very unlikely to get any advantage, and you may even be running a serious risk of getting in trouble out of the opening.

With that being said, nonstandard openings are not to be written off completely, and at the 1700-1800 lichess rating range they can be quite a potent weapon, catching many players completely off-guard.