same as php hate, mysql had some questionable design decisions and legacy hacks, which are mostly not that relevant today except for causing some warts on the interface (like e.g. utf8mb4, mysql_real_escape_string)
You say you "advise" and don't give any specifics. So why Kotlin over the myriad of other options? Picking a LAMP stack is picking a stack that is battle tested — nothing wrong with that for new projects.
Kotlin is basically Java 2.0. Kotlin has really great developer ergonomics and a huuuge ecosystem of Java libs you can easily use since you are on top of the JVM which (a much better tech than PHP). Kotlin being quite high-level fits well with webdev (I'd only use Rust for super perf critical web dev for instance). Kotlin is OO-code (easy for new devs) with lots of FP goodness (as that's where the party's at).
Big shops with big legacy PHP code bases all move away from it.
LAMP = Linux (sure), Apache (no-way, use NGINX or in app web server instead), MySQL (sorry, Postgres won) and PHP/Perl (these langs are going the way of the Dodo).
So LAMP is a bad choice nowadays. I'd say it has been since Ruby on Rails 1.0.
I prefer languages that have been designed with this in mind. Kotlin in this case goes a long way.
Golang is shit IHMO. No null-safety. No sum types. I dont know what Rob Pike was thinking when he designed this. Total disregard for the last 40 years of innovation in software engineering. Sad.
PHP is also something I'd not advise anyone to use on a greenfield app unless you have really good reasons for doing so.
There are much better --also very conservative-- stacks available for free (and no, those are not JS based).
For instance: Kotlin, http4k, JTE/KTE (or kotlinx.html), SQLDelight, Postgress.