All these companies competing with each other and all trying to bring products at a price that is competitive. They all have to cut costs to stay profitable. Cutting cost leads to lower standards with components. Many people don't realize that these consumer grow lights are a niche market. There is so much competition these days that using a MIL-spec AMP connector is not a viable option cost wise so they source lower priced components and the lower cost comes with lower quality which is responsible for the failures that people are experiencing.
It's not just a Mars Hydro issue. They don't make the connectors and other companies are using connectors that are no better in quality. It's how a company deals with these issues if/when they arise that matters. Some handle it better than others.