Even if you drop small molecules and focus on antibodies, it's not like it's all that easier.
If you want to fix MCL you figure out how to engineer a genetic payload that targets B-cells IFF they express particular genes, and reengineer those cells' genomes to either no longer reproduce abnormally, or shut them down. You do NOT covalently turn off an entire class of kinases in the ENTIRE body...
And that's the success story. Antibodies are just the tip of the protein-iceberg. They're the 'same things as a small molecule' but in protein form - baby steps into a whole new world. Sure, they can bind to stuff tightly, but if that (alone) is what you're aiming for, then they're not being used to try to fix the problem or engineer a way to the solution. There's lots more that we could do if we started actually engineering the proteins and their interactions, and delivering them in directed ways. We have access to those primitive engineering tools, but instead of focusing on those nascent tools, we're polishing up the old hammer.
First off, the medical science is itself based on wrong theories, see what Pasteur himself had to say "Terrain is everything, the Germ is nothing", yet the medical industry is hell bent on developing cures based on germs.
As for cancer,HIV and other incurable diseases many researchers have come forward, some of them include Rife, Nessens, William Koch, Oxygen therapy, Lakhovsky MWO, Priore device etc.
Unless we revise the our theories and procedures and look into the works of above reseachers, we will never find the cure.
The pharmacy of the future will be entirely curative to non-invading diseases, will repair the DNA that's been mutated, will express or inhibit the proteins that need to be expressed or inhibited. And small molecules will be the payload of these fancy protein-based nano-machines. But this hunt to bring down the cost of those small-molecule targets at the cost of the reputation of the science itself might be foolhardy when the cost is near-infinite in the first place because they're looking from the wrong perspective.
tldr; Pharmaceutical companies' hammer that worked so well against the nails of bacterial infection is in no way suited to the plumbing of cancer. And now they're 'investigating the plumbers' to figure out why their fancy new 50-billion-dollar "water-hammers" don't work so well to unclog pipes.