I don't remember any rider ever stating in January that their main target of the year was lombardia. It's more of a "I'll show up with whatever fitness I've got" or "I missed my main target due to injury" type of deal.But if you look at the same era for LBL you got guys like Gerrans, Iglinski, Jungels and Poels. I'd reckon that maybe even more under par than Lombardia.
And to go beyond the Lombardia debate, all of the climbing monuments/one days are less important to the best climbers than the flatter/cobbled classics are to the best Flandriens. Because Liege etc compete with GTs for the attention of climbers. For example Vingegaard doesn't bother with Liege although I have no doubt he would do pretty well. That diminishes Liege somewhat. This is also why you see the GT also-rans like Pinot, Mollema winning Lombardia. Liege at least has the draw that it's near the other Ardennes races so more climbers target that part of the calendar for a peak.
(That said, unfortunately this year a lot of the best Flandriens were injured so we didn't get any epic battle. Ish happens.)