I have found the purchase protection on the Amex Platinum useful. My one-month-old Google Pixel 2 started misbehaving and Google would only replace it with a refurbished unit and refused to pay to for an authorized repair. However, Amex's purchase protection covered the repair at a local authorized service center.

However, Amex Platinum does not provide travel insurance for trip delays or cancellations. This bugged me last month when I had to reschedule a flight to California and pay the outrageous $200 change fee of American Airlines. My colleague had booked his flight with a Chase Sapphire Reserve, which does have better travel insurance, but still wouldn't cover the circumstances of the rescheduling.