with time, we tend to forget the context of how those wins were achieved and only statistics remain to morph the reality. 2017 and 2018 were years of mercedes and ferrari battles.
when red bull came to testing in 2017 with a bland car, everyone thought they have a spec b in progress. however that was just a fantasy. red bull wanted to try low drag package and hadn't fully utilized the 2017 aero changes and that left them far behind both mercedes and ferrari and they could never recover.
red bull's first win came in the 8th round of the season in the infamous race of baku where the leaders, hamilton and vettel engaged in incidents (safety issue for hamilton and penalty for vettel) and were out of contention for a win. it them allowed ricciardo to win the race with a sure shot "2nd place to stroll in a williams", which was robbed by bottas in the last second ditch. stroll finished on podium for williams.
red bull's second win then came in the 15th race of the season in malaysia. vettel had engine issues and didn't participate in qualifying. hamilton took pole despite a struggles with their new upgrade package, which was ripped off for qualifying. kimi qualified second and verstappen third. on race day, kimi stalled before the race started with an engine issue and was off the race. hamilton struggled for tyres and was passed by verstappen on 4th lap easily.
their 3rd win of the season came in mexico where the altitude has helped renault engines to perform better due to their relatively smaller turbo. mercedes were also struggling for slow corner speed in 2017 and it was evident in mexico. vettel got pole, verstappen 2nd and hamilton 3rd. at the start verstappen jumped vettel, there was an incident and vettel lost his front wing and also induced a puncture to hamilton. both protagonists were out of contention.
i can add context to 2018 also, as every one of those rb wins in 2017 and 2018 were scraps collected, being a distant third best team.
this is the first year in testing where they have looked the best and the optimism is justified. this discussion started with why mercedes cannot be brushed aside as they have been the best overall package and red bull hasn't done particularly good job of building leading chassis in the last few years.