Reason not to play the London System as white

imgflip.com/i/1butpu

most engines will always play early c5, Qb6 to harass b2 pawn, and Nh5 to harrass the f4 Bishop, d6 and eventual e5 break.

Could you possibly provide an example from a real game? :)

d6 is illegal. As the London should start with d4-d5 Bf4...

No but in your picture you did a move order mistake. 2.Bf4 is inaccurate after Nf6 where you should play Nf3 in between. After d6 you wouldn't play Bf4 neither. So how did you got into that position?

I guess the position might have been created after the moves
1.d4 Nf6
2.Bf4 c5
3.c3? (e3!) d6 ( because after 3...Qb6 4.Qc2 black would have taken the pawn on d4
4.Nf3 Qb6
5.Qc2 Nh5
Stockfish giving a slight advantage to white after retreating the bishop to its original square or to d2.
White made 1 inaccuray but black didnt take advantage of it and didnt play Qb6 but3...d6 which led to the final position.
Correct play would have been:
1.d4 Nf6
2.Bf4 c5
3.e3! and if Qb6 now
4.Nc3!...take a look at the database what would happen if black takes on b2.

d4 Nf6 Bf4 bussiness is very normal even at the highest level

or
1.d4 Nf6
2.Nf3 c5
3.c3 d6
4.Bf4 Qb6
5.Qc2 Nh5

it looks like this way is easier to reach the position but 2.Bf4 might have been a little more precise to the London system

It is not played much at grandmaster level. Take a look at the win-lose rate. After d4 Nf6 Bf4 and black is already equal to slightly better. It's playable but again not a good theoretical continuation.

Carlsen and Grischuk repeatedly played this. I believe they are GM's.
Me personally I love the London system. I played before I actually knew that it is called the London. I started with 2.Nf3 but now I switched to 2.Bf4 which is a little more precise.
Maybe I dont have big advantage in the opening but definitely I am not worse. A lot of good players dont know what to do when I throw it at them.
Here an example
cs.lichess.org/5AQ6NAXFCX9T

@jan_braun london system is said to be boring. but oh well, since it's carlsen..

@Erza_Scarlet Yes, I know it is considered boring ( it seems like you know what is considered to be true by majority )but I dont care. I like those positions. I played this earlier than Carlsen ;) So I was happy that he started to play it too.

@Kitty-Meow #1
GM Kamsky plays London very often with good successes. GMs Carlsen,Giri,Kramnik and some others also play it every now and then.
Are you saying that we, chess amateurs should stop playing it against other chess amateurs ? :-)