The post discusses three major flaws in Single Instruction, Multiple Data (SIMD) Instruction Set Architectures (ISAs). These flaws can hamper performance and efficiency. Firstly, the lack of flexibility in SIMD can limit adaptability to diverse computational tasks; secondly, it demonstrates inefficiencies in handling branch-intensive workloads; and lastly, SIMD's reliance on specific data alignment may lead to underutilization of processing capabilities. This highlights a growing need for evolving ISAs that can better accommodate modern computational requirements. The linked comments emphasize the broader utility of SIMD beyond just basic linear algebra routines, suggesting there are unattended applications worth exploring.