That's the idea behind an Axios article that came into my news feed today. At first I snorted, as my experience has been quite the opposite, as testified by the popularity off our "Pinot Selections" wine club.
My theory was that this salacious headline was reporting some non-news, the well-known fact that when a wine explodes in popularity (as with any product made from a limited resource), attentive growers flood into the market to get in on the new gold rush. Not surprisingly, not all of those new growers (i.e., MOST) have land that is particularly well suited to Pinot.
As I read the article, that is exactly what the author reported. They simply reported that agricultural data for the past 15 years (since Sideways was released) shows Pinot vines being planted in areas best suited to hardier grapes. They key excerpt:
"...large winemakers [emphasis is mine] wound up growing not-so-good pinot noir grapes in inhospitable land, then blended the wine produced from those grapes with the good stuff from coastal areas, thus stretching their supplies further to accommodate higher demand."
Neil Irwin, Axios article "How the Movie Sideways May Have Ruined Pinot Noir"
Conclusion
Honestly, neither you nor I can tell what decision a winemaker makes while making their wine. However, I don't know a a small producer of hand-crafted wine that would even dream of diluting the quality they strive for. Producing the BEST possible product is their single vision, their guiding principle. It is the reaon they get up every morning. It is their "WHY".
So, pinot lovers can relax. Avoid the big producers, be willing to spend enough to support the small producers (average price is now about $42 for a good Pinot), and focus on producers whose name is on the label.