Yes, the first ST version in 1987 had bugs. But WordPerfect fixed bugs for the next four years, and by 1988 was in good shape <https://www.atarimagazines.com/v7n1/wordperfectst.html> despite, as I said, the huge problem with piracy (See, for example, the author of the 1987 review you cited writing at <https://archive.org/details/ST_Log_Magazine_Issue_21/page/n8...>. If the ST version were so useless why would he have bothered to appeal to the community?). As I said, the odds of a random no-name ST or Amiga word processor coming anywhere close to WordPerfect's power c. 1989 are zero.

Piracy always exists. The question is to what degree. On the PC the bulk of the market is business customers, where piracy is relatively minor compared to legitimate sales, and corporate customers have a lot of power when they complain to vendors; this is why copy protection more or less disappeared for PC business software after the mid-1980s, with Lotus being probably the last to comply by getting rid of the universally detested key-disk system. On the ST and Amiga the business market more or less didn't exist (no, musicians on ST, or small-town TV stations using Video Toaster for Amiga, aren't meaningful in number or percentage by comparison), so potential sales are limited by a) the far smaller size of the overall market and b) the far smaller percentage of customers within said smaller market paying for the product.