OK - file size and disk space - another variable to throw into the mix. Let's look at this logically in terms of priorities. Disk space is cheap, time is expensive. The smallest image file is the raw file. Those 4 or 5 KB files are metadata files. ACR and LR have them too; DNG embeds the information. These don't bloat disk space. If we can go from importing the image to print without Photoshop all in the raw converter as Lightroom is structured to do, the disk space is confined to the raw file size and perhaps an XMP of 5 KB.
If we need to work in Photoshop regardless of all the adjusting done in the raw converter, we render the image and then we store at least the size of the rendered image plus the raw file, regardless of which converter we used.
If we import the raw file as an S.O. into Photoshop, yes, the Photoshop file gets bigger, BUT we also have a universe of image adjustment flexibility through the whole processing pipeline without having to redo all the work in PS if we find at some point during the PS work, we should have made some further adjustments at the raw stage which would have been better. So we buy a larger file as an insurance policy for avoiding perhaps considerable wastage down the road. Maybe we draw on that insurance, maybe we don't. After processing the image, if we think we won't need the insurance, we can convert the SO to a Background layer and save as an ordinary PS file.
The bottom line here is that one suite of programs provides this flexibility and others don't. If we need or like the expanded range of options and their associated potential efficiency to work with, file size is not the main distinguishing issue or even the decisive one.