Don't know how much it has changed in the last ten years since I raced my last road race, but I podiumed on a Chinese bike that cost a grand. I at no point felt that I was disadvantaged compared to guys on their S works and the like. I wasn't the only one using cheap parts in races.
Also recalling a guy who used to be on the forum being competitive in crits on a budget Btwin with a triple.
Harry Mack raced the Nationals on a cheap Chinese sourced bike and was competitive. The junior world champion was on a Chinese bike last year. All substantially cheaper than equivalent brands that want to charge you five grand plus for a decent race bike.
The biggest factor is the engine.
Isn't equipment cited as one of the reasons why we've seen a 10% boost to both average speed in races and times up key climbs in the last handful of years?