When you have vectors such as text or logos etc. what happens is that the RIP (raster image processors) converts it to raster just before printing, and it converts it to a much higher PPI than what you may do.
If you take a vector text and convert it to a bitmap, say 300 ppi - that won't be enough to render the text in good quality. You'd have to use 1200 ppi or even 2400 ppi.
If you rasterised your vector and placed it in a file, then when making the PDF there is an option to downsample raster images to a certain amount of DPI. Here you may find that your 1200ppi rasterised vector is now being downsampled to 300 DPI - so it would be best to choose no downsampling.
Where vector is a huge advantage prior to RIPing is that the RIP does the conversion on output, it uses the best settings for that particular printer/platesetter/film setter/ to produce the vector in the highest quality.
Vectors are also scalable to any size imaginable. Use that vector on a business card, or on a building wrap. However, if you rasterised the vector for the business card, you couldn't possibly scale that to the size of a building without causing major pixelation.
In short - the RIP manages the conversion to raster, and uses the best setting. You just need to place a Vector and leave the math to the printing device.
My advice for text is to if you have to rasterise it, make it at least 1200 ppi, And don't downsample it.