I'm going to disagree with that assessment. The statement is much too broad to be taken at face value - sorry. There are many reasons for spoiled foliage that don't fall under the category "light-related". In this case, it's highly doubtful too much light was causal. It looks like a bacterial leaf issue (Pseudomonas?) or something physiological, like the plant being too cold or having been exposed to a sudden temperature drop. IOW - a possible bacterial leaf infection or chill injury.