:::The tool is what people are using to judge size considerations these days.  Moreover, the guidelines don't clearly state 50k as the uppermost.  WP:SIZE says "Readers may tire of reading a page much longer than about 6,000 to 10,000 words, which roughly corresponds to 30 to 50 KB of readable prose."  The word count is the key measure here; the readable prose numbers are an estimate of what word counts translate to, an estimate that happens to be off a bit in this case (as the "roughly" concedes may happen).  Then later in WP:SIZE are the actual prose size guidelines, which say "40k-60k May eventually need to be divided (likelihood goes up with size)", "60k-100k Probably should be divided (although the scope of a topic can sometimes justify the added reading time)", and "100 KB or more Almost certainly should be divided".  So a 9,500 word, 59k prose size article fits within both guidelines for remaining as it is.