That time Linear algebra was of no use? Possible may be, Electrical, civil and Mechanical engineerings were mainstream

To a degree, yes. That's not _that_ long after Einstein had to seek out math experts because he didn't know the theory behind 5x5 matrices. Math professors I know who started much later than that didn't really get how linear algebra was useful when teaching ODEs. It's not that it wasn't useful, but it wasn't commonly used.