Learning assembly is extremely valuable, depending on what you are going for. Are you trying to only stick with web development? If so, then maybe it's not that useful. However, even then, how will you even know if you want to stick with web dev if you don't first try other types of programming?
I can tell you that I wouldn't be where I am if I didn't learn assembly. Having assembly language as a skill on your resume and being able to answer assembler questions in technical interviews is a HUGE advantage for many jobs which involve low-level programming, reverse engineering, optimization, security, etc... I am a team lead and I can tell you that if I see assembly on someone's resume or portfolio, I am much more likely to interview them for a software security engineer position than those without it.
Even if the job doesn't require assembly, the chances that someone will be fluent with assembly and understand such low-level programming, but struggle with javascript or python is very slim. However, there are plenty of folks who can do a .contains() or .map() but have no clue what the hell is going on under the hood.