They made a lot of things right. But they had a centralized planning of production that eventually blowed everything. Until the 60s - mid 70s soviet technology was about equal to the western (and not only in optics) since they copied German technology and upgraded it gradually. But they lost the Silicon (electronics and informatics) Revolution, spent vast amounts of money for weaponry (the Star Wars was the coupe d' etat), they had no interaction with the advancing Japanese technology that spermed US and Europe and they couldn't reach massively the rich western markets that wanted shinny and colorful products and gadgets and not the crude simplistic objects of the Soviet design. Yet, for decades, astronomers bought the TAL, LOMO and other Soviet refracting and Maksutov telescopes because the Zeiss were astronomically expensive, until Celestron offered the orange tube 8" Cassegrain and Dobson invented an alternative to the complex and heavy equatorial mount.