Usually asking someone with more experience for input should be productive, unfortunately not everyone is willing to provide information unless the outcome is more beneficial to them.
Most people here will give you an honest account of their experiences, it's just that experiences tend to be subjective.
On this topic, on the one occasion my CMDR did make use of the interdictor against enough other CMDRs to get a feel for it, his success rate was probably 60% against those that resisted, and this was with me being very inexperienced in it. However, this was mostly against equally inexperienced targets and was way back in mid-2015; I have essentially zero experience interdicting unwilling player-piloted targets since.
I can count on one hand the number of times my CMDR has tried to fight CMDR interdiction which is far too small a number for me to even form a subjective opinion about it's difficulty. So, I have only second hand experiences to quote if asked to comment.
Ultimately, I either want to fight, in which case submitting is easier. Or I do not want to fight, in which case submitting is easier. If I participated in wing PvP more where tying someone up via interdiction, delaying an engagement, or pulling just the right member of a wing first could provide a tactical advantage, I'd be far more inclined to improve my skills in this area. Same would go if I were a frequent participant in activities that were time sensitive that required my CMDR to be somewhere specific, but the game doesn't really incentivise this very well, at least as far as my CMDR is concerned. The only reason I go to most CGs is to shoot people and be shot at by people; space is big, even in the bubble, and my CMDR can't be bothered to care about the fate of most of it...and the purely monetary rewards are both meaningless as well as being outstripped by half the stuff on any given mission board. There are certainly some exceptions, where my CMDR has a vested interest in what's going on in an area, but these rarely coincide with an active CMDR presence...it's mostly BGS stuff where the opposition isn't even in the same mode.