Fair enough, I used to be scientist (a very bad one that never amounted to anything) and my perspective has been that the major barriers to progress are:

We've just got all the low hangingfruit
Science education isn't available to many people, perspectives are quite limited consequently.
power structures are exploitative and ossified, driving away many people
industry has too much influence, there isn't much appetite to fund blue sky projects without obvious short term money earning applications
patents slow progress
publish or perish incentivises excessive volumes of publication, fraud, and splitting discoveries into multiple papers which increases burden on researchers to stay current
nobody wants to pay scientists, bright people end up elsewhere