Not true at all.
I am a home brewer and for a long time I preferred guinness bottles for my brew based on their appealing appearance. They were an extra pain because you had to get the plastic widget out of the bottle before you could sterilize it. I fabricated my own widget extraction tool out of a ham slicer knife and invented my own technique for getting the widget out.
NO, they only recently stopped using the widget in the bottles...like the last 2-3 years.
No, for years you could buy Guinness in regular 12 ounce bottle six-packs, or you could buy them in bottle six packs with the widgets or can 4-packs with the widgets.
Sometimes you would see all three at the store at the same time. The regular bottles were clear, the widget bottles were colored over and a different shape.