"Marketing takes a day to learn. Unfortunately it takes a lifetime to master."
Philip Kotler

Marketing must have some significance. But in the end marketing is completely useless, if you can not deliver what you promise.
So in the end marketing is not about the product but about the customer, what are his needs, how can his life become easier, how can his costs be lowered, how does he want to be communicated with. And then look at your product from the eyes of your customer. So what those guys at Heinz did was great, probably not because they took a flaw and made it a strength, but because they found that customers do not want to hurry when eating. Probably the reason why they stopped using the slogan several years ago, everybody is so hurried, that telling them that you can use a bottle of ketchup to relax is completely useless.
And if marketing wants to get really effective it should not only include the getting a product sold fase but also the production fase (the strength of Apple) up to the moment the product gets discarded.

Today's entrepreneurs remind me of ancient warlords like Julius Caesar and Alexander the Great; aren't they all up for conquering the world? I truly believe that good marketeers are of all times.

Marketing is a true skill. Think back to the time when Heinz with its glass bottle was challenged by plastic bottle vendors (which gave a much better squeeze). Heinz was panicking and they were tempted to drop their glass bottle and also go mainstream. But then a brilliant marketeer came along and invented the slogan "Heinz, the slowest ketchup in the west".
That was PURE genius. To turn a perceived weakness back into a strength true to your product. Sales veered back up again mostly due to them not giving in to plastic bottle pressure but focus on their own strengths...