SwiftUI Text: line height of 1st line ≠ HIG text style - why ?

[this is a copy with new 'SwiftUI' tag of a - still unanswered - questions with 'WWDC20' & 'UI Frameworks' tags - there seem to be no way to add tags after posting ...?]


So here it goes:


The line height of the 1st line of a SwiftUI Text view is different from what the HIG specifies:

For example (Content Size Category = .large , @2) :
(Please see code below)

• 10 lines of Body - HIG             =  220.00 pt

• 10 lines of Text with Body         =  218.50 pt

• 10 x 1 lines of Text with Body   =  205.00 pt

The difference depends on Content Size Category and resolution of the device.

Behavior is the same in Xcode 11 (macOS 10.15.5) and Xcode-beta 12 (macOS 11.0 Beta (20A4299v))


Questions:
Why is that?
What’s the benefit of that?
Is there an easy way to specify HIG line heights - so that the frame size of the Text is a clean multiple of HIG's line height?


Thanks!

Code Block Swift
import SwiftUI
struct LineHeights: View {
	var body: some View {
		HStack(alignment: .top, spacing: 0) {
			//  1x10 lines in "L Body" - height = 218.50 pt - why?
			//  =======================================================
			Text("Hello, World! 0\nHello, World! 1\nHello, World! 2\nHello, World! 3\nHello, World! 4\nHello, World! 5\nHello, World! 6\nHello, World! 7\nHello, World! 8\nHello, World! 9")
				.frame(width:120)
				.overlay(Measurement(color: .green))  //  reads:  218.50pt  (@3: 218.33pt)
			//  10x1 lines in style "L Body" - height = 205.00 - why?
			//  =======================================================
			VStack(spacing: 0) {
				Text("Hello, World! 0")
				Text("Hello, World! 1")
				Text("Hello, World! 2")
				Text("Hello, World! 3")
				Text("Hello, World! 4")
				Text("Hello, World! 5")
				Text("Hello, World! 6")
				Text("Hello, World! 7")
				Text("Hello, World! 8")
				Text("Hello, World! 9")
			}
			.frame(width:120)
			.overlay(Measurement(color: .yellow))  //  reads:  205.00pt (@3: 203.33pt)
			//  Apple HIG:  10 lines in "L Body" - height = 220 pt
			//  =====================================================
			Text("Apple iOS HIG:\n10 x Body = 220 pt")
				.font(.caption)
				.frame(width:120, height: 220)
				.overlay(Measurement(color: .blue))  //  reads:  220.00pt  (@3: 220.00pt)
		}
	}
}
struct Measurement: View {
		let color: Color
		var body: some View {
		//  measure
		GeometryReader {
			geometry in
			ZStack(alignment: .bottomTrailing) {
			//  color
			self.color.opacity(0.8)
			//  display
			measurementText("\(geometry.size.height, specifier: "%.2f")")
					.font(.title2).fontWeight(.bold)
					.foregroundColor(.red)
			}
		}
	}
}
struct LineHeights_Previews: PreviewProvider {
	static var previews: some View {
		LineHeights()
	}
}

(I'm struggling with reformatting the source code - so apologies if it looks scrambled - the original post (with same title) is OK)