I'm just not sure another year in the lower series would change the story for Suarez. I agree to a certain extent you don't want to rush in the Hemric sense having never even won a race in Trucks or Xfinity. At the same time when the opportunity presents itself to go into a high quality Cup car, from a driver's standpoint you better be ready and you better take it. Suarez had 2 years in Xfinity with 3 wins and a championship, he was showing good promise, maybe he did require another year to hone his skills, hard to say if that would have made the difference.
2-3 seasons seems about the norm these days though. Larson only did 1 xfin season before being brought up (he may have been considered rushed). Byron did 1 in trucks 1 in xfin and he's looking like he's going to develop into something special in Cup. Chase did 2 seasons with similar success to Suarez before being brought up. Stenhouse is a good example of a full 3 year development in Xfinity/championship/wins galore, and his Cup career still ended up less than stellar other than the plate track wins, granted Roush falling off the map didn't do him any favors.
There's just no guarantee and I'll continue to be puzzled by it. Ultimately I think you either fall into a successful team chemistry/car/cc that can further progress you at the Cup level or you don't. If you lack the driving talent to measure up and are missing on all of those other things, then it ends up even worse.