It's not merely a PR statement, he actually provided context but I guess you can draw whatever conclusions you want from it.
It seems to me most British football fans look down on every other top 5 league. Spain was only good because of Real, Barcelona and Atletico despite Sevilla dominating Europa league, Germany and France have one team farmer's leagues, serie A is slow (all of them are apparently), etc. Lukaku has proved himself in England though
The top scorers in Serie A are always an odd selection though and not one that supports the argument that it’s difficult for forwards to score in that league given the relative quality on this list and the numbers they’re able to produce:
2020/21:
Ronaldo - 29
Lukaku - 24
Muriel - 22
Vlahovic - 21
Immobile - 20
2019/20:
Immobile - 36
Ronaldo - 31
Lukaku - 23
Caputo - 21
Zapata - 18
2018/19:
Quagliarella - 26
Zapata - 23
Piatek - 22
Ronaldo - 21
Milik - 17
2017/18:
Immobile - 29
Icardi - 29
Dybala - 22
Quagliarella - 19
Mertens - 18
2016/17:
Dzeko - 29
Mertens - 28
Belotti - 26
Icardi - 24
Higuain - 24
Immobile is the stand out example for me because I thought he looked really poor at the Euros, as well as having a torrid time at Dortmund, yet he’s consistently been the best goal scorer in Serie A over the last 5 years.
And then another example would be Dzeko whose best tally at City was 16 but then goes to Roma, at 30 years old, and scores 29. Even Zlatan was scoring at a rate that was comparable to his peak last season, before his injury, at 39 having spent the last few years playing in the MLS essentially recovering from an ACL injury.
Serie A just seems to be a league where CFs, particularly physical ones, have a relatively easier time of it when it comes to putting up big numbers that they’d struggle to match elsewhere.
Having said that, Lukaku has for the majority of his career been a 1 in 2 striker so I fully expect him to continue in that vein for Chelsea, especially if they give him the same number of chances they were gifting Werner last season.
20 goals next season for Lukaku and about 253 finger points seems a solid guess.