Why there are no famous painters called Johnson

Imagine this passage written by someone like Dickens, who probably would have thought it quite innocent at the time.

My good friend Bennett came up to me one day. As we were standing in the drawing room, he coughed and remarked wistfully:
'I couldn't help noticing your Johnson in the salon. It's quite magnificent.'
'Thank you', I replied. 'I've always been proud of my Johnson. I like its vivid coloring -- the reds and pinks.'
'Well, who amongst us does not enjoy a Johnson? It's not a fake, is it?'
'Oh no,' I chuckled. 'It is most assuredly the genuine article. Would you like to see more Johnsons?'
'You have more?' he cried avidly. 'Please show them to me posthaste!'
Pleased with myself, I went to the dining hall in the west wing. There, lined up along the wall, were no less than seven Johnsons, in a variety of sizes.
My guest gasped in admiration. 'My dear friend!' he exclaimed. 'I have never seen so many Johnsons assembled in my entire life!'
'Feel free to enjoy them at your leisure,' I said.