Nadal and Federer have been at a very different place from Venus for a very long time. 2017 was an anomaly for her whereas (insert Federer and Nadal's bad years this decade) have been anomalies for them. She's spent most of the last decade being a shell of the player she once was. Truth is, save for a few Wimbledon in the second half of the noughts, she changed post-2003 and never was the same as before. Now she is like two steps slower than she once was.
Lol considering she has an auto-immune condition (and again, I personally know how that feels), trust me she has zero reason to be dissappointed.