Why's everyone posting song lyrics? may as well give it a go myself
Are you ready, Bob?
Yes!
What about you. Lofty?
I'm a bit scared
Okay, team, let's go!
One, two, three, four, five
Everybody's outside, so come on let's ride
To the builder's yard around the corner
The gang's all here and it's time for us to do what we wanna
There's a house with a roof that leaks
It's an urgent job and it could take us weeks
There's Dizzy, Lofty, and Rolly too (That's me!)
And Wendy always knows just what to do (That's right)
And there's no job too big or small
With Scoop and Muck we can do it all (Yeah!)
Metal, brick, or wood - it's all good
And we can always send in the tractor
A little bit of timber and a saw
A little bit of fixing that's for sure
A little bit of digging up the roads
A little bit of moving heavy loads
A little bit of tiling on the roof
A little bit of making waterproof
A little bit of concrete mixed with sand
A little bit of Bob the Builder man
Jump up and down and move it all around
Mix it up to the sound
Dig a hole in the ground
Take one step left
And one step right (Okay)
One to the front (Right)
And one to the side (Yes)
Clap your hands once and clap your hands twice
And if it looks like this then you're doing it right
A little bit of timber and a saw
A little bit of fixing that's for sure
A little bit of digging up the roads
A little bit of moving heavy loads
A little bit of tiling on the roof
A little bit of making waterproof
A little bit of concrete mixed with sand
A little bit of Bob the Builder man
Mambo number six and seven, eight
Mambo Number Five!
A little bit of timber and a saw
A little bit of fixing that's for sure
A little bit of digging up the roads
A little bit of moving heavy loads
A little bit of tiling on the roof
A little bit of making waterproof
A little bit of concrete mixed with sand
A little bit of Bob the Builder man
There's Rolly, Lofty, Scoop, Muck, and Dizzy
So much work to keep us all busy
And can we fix it? Yes, we can!
With the team and Bob the Builder man
A little bit of Bob, Bob the Builder man
Mario Party is a party game because it has its own self-contained mini games and is played on a virtual game board. While said games can be action or platformer oriented, the overall main framework of the game isn't either of those things. It's a literal board game. You roll the die and that determines where you land and what you do.
Smash has heavy party game elements, but it isn't structured around a party framework. It has/had mini games with platformer or party elements but the main game is entirely built on a fighting game framework. Even in the original, characters' moves and archetypes were still based around frame data, range, damage, hitboxs, and other elements we associate with fighting games. You still have your heavy characters, your zoning characters, your aggressive characters, etc. You still play with the objective of dealing damage to KO your opponent in ways that aren't similar to other genres.
If you were to ask any layperson on whether Smash was closer to Mario Party or Street Fighter, I'm going to guess they would say Street Fighter or both. It's not something that required any real thought or analysis in the first place. You can just watch a match, even a casual match, and see it shares more similarities with fighting games than anything else.
It seems to me this all started when the 40-year-old manchildren in the FGC became self-aware that the rest of society does not look kindly on their hobby at their age. And that they are trying to use Smash as a sort of scapegoat to say that Smash is for children and their game(s) is for mature, competitive players that is a respectable sport, etc. Because I certainly don't remember seven-year-old me worrying about whether Smash 64 was fighting game, as it was rather obvious.